Is the caro-khan the most solid against e4?

French defence is best against e4 . it's exchange veriation is similar to Caro kaan .

you are the first person to correctly spell caro kann in this forum.

And yet you can't spell it yourself.  Capital C, Capital K, and you're missing the hyphen!

Not really...

I use the Caro-Kann all the time. It's a great opening, but it tends to lead to a lot of draws, so watch out for that.

Not true at all!

Speaking as someone whose primary defense to 1.e4 is the French and whose secondary defense to 1.e4 is the Caro-Kann, neither compares to say, the Berlin Defense, when it comes to solid, and if you compare the two, the Caro-Kann is by far more solid than the French.  The French is a violent defense, second to certain lines of the Sicilian.  I've blown players as White off the board in under 25 moves in the French, and I've gotten my own butt blown off the board in under 25 moves as well.

For example, I doubt anybody would ever refer to 1.e4 e6 2.d4 d5 3.Nd2 Be7 4.Ngf3 Nf6 5.e5 Nfd7 6.Bd3 c5 7.c3 Nc6 8.O-O g5! as being even remotely solid!  The Black King has no real safe haven, and is relying on the attack alone!  White's best here is 9.dxc5, clearlying out the d4-square for the Knight when Black goes 9...g4.  Naive players that have no clue what they are doing and don't truly know how to play the Tarrasch will try to play 9.h3?!, which is dubious at best!

I have a tournament in a month and I'm thinking about adopting the french because the lines and plans are easier than the e5 and I need to win games, and the caro, for what you have discussed here, is drawish.

I never said I could spell.

E-5 has gained back popularity among the top level players. Who knows what is best!!

 Is the Caro-Kann the most solid against e4?

These statistics are from chess.com as at 29/04/2018, and are similar on other databases. The safest opening is the one with the highest percentage of draws, i.e. the Ruy Lopez. But the downside is that you will suffer for a long time, with less chances to win than the others. It is well known that white usually maintains lasting pressure, with not many pieces being exchanged in the opening, Yet the Caro-Kann has a similar drawing percentage as the Ruy Lopez, but with similar winning chances as the relatively riskier French. Therefore on balance you should choose the Caro-Kann. It has far less theory than the others, and is easy to learn. Getting a book would be a good start, to learn the main variations.  

I should add that one major annoyance with 1 ... e5 is that a large percentage of white responses will not be Ruy Lopez, but Giuoco Piano or Scotch. So you can waste a lot of time studying the Ruy Lopez and not get to play it about a third of the time. But that's another advantage for the Caro-Kann, in that you have not wasted any time.   

You shouldn't be too disappointed though, as these statistics show that you will have more winning chances than with the Ruy Lopez. That is as long as you also study the aforementioned openings. These statistics are from Masters. For mortals it may be best to take it slowly, and be content with the Caro-Kann, knowing that you won't be surprised into playing something that you have not prepared for.

That's wrong. Do really think < 2000 players learn all the theory? Everybody who is into gambits and likes to attack will be successful with that opening. So If you only prepare a few moves deep you're already have an advantage because your opponent doesn't know all the theory.

Note that just as no pair of shoes is the right size for everyone, no single opening is the best for everyone.  It depends on a combination of skill level in tactics and in strategy, your vs your opponent's familiarity with the opening, your tendency to want open vs closed positions, etc.

Personally, I like the Caro-Kann a lot because it fits my style of play. The chess.com Explorer says I've won 6, drew 4, and lost 4 with it against strong (usually 1600-1900) mostly daily competition.

It allows me to get my Queen Bishop into play early which the French doesn't do at the expense of taking two moves to get my pawn to c5 to begin a Q-side attack compared to one in the French. That works for me, but it might be too slow development for others.

I also like its cousin the Slav Opening (6 wins, 1 draw, 5 losses) against 1 d4, which has similar positions to the Caro-Kann (I usually answer 1 d4 with ...c6 hoping for 2 e4 d5 and the Caro) and recently began playing its mirror image with a move-in-hand, the London Opening - where c5 can often be made in 1 move if you want that position.  I should have a positive record in the London soon.

Good question!

My personal opinion is to not worry about openings until not having a repertoire is actually holding you back. Opening principles and one or two openings, any opening, is enough for most.