What is the most forcing opening for White?

Let's say that a chessplayer wants to study a decent opening for the first player: what is the one were black correct answers are fewer and so the opening is relatively easy to study? Let's say we're talking about the first 4-5 moves for both players. Probably it's a d4 opening I guess but which one?

Regards

there's no such opening....and if there is...it's probably crap anyway.just play something decent (e4 and/or d4,c4,nf3) and you'll be fine.

play scotch, e4 e5 nf3 nc6 d4

Parham Attack

1. e4 e5 2. Qh5 is pretty forcing.

But in all seriousness, 1. e4 is probably best for limiting Black's options.

This obviously will not fall into the "forcing" category but you can play the Colle or London systems against just about anything with white. The truth is that on move 1 black has yet to make a mistake so you can't really force anything of consequence in the opening.  I guess I agree with Blackwaive's comment "But in All seriousness, 1. e4 is probably best for limiting Black's options" but black still has a ton of responses to 1.e4. 

Against any first move, black has a wide range of possibilities and potential future plans.  That said, a good beginner repertoire can cut down black's good, strong rejoinders by a pretty good margin, guaranteeing that you'll either be playing on familiar ground, or be playing against sub-par moves.

Something like:

-QGA - 3.e4

-QGD - exchange

-Slav - exchange

-Any 1...Nf6 - Tromp

-Dutch Bg5

E4 stops when your opponent plays the centre counter

Not really, after Queen takes you play Nc3, and have a knight developed, while your opponent must take a turn retreating his queen.

 Thank you for your answers. Anyway I was referring to the first 4-5 moves not just e4 ,d4. Anyway I was thinking about these:

Colle

Colle with Bb2

London System

What about the Trompowski (+Levitski Attack if d5) and the Torre Attack?

Regards

OMG Gavinator has refuted the Centre Counter!

Yeah ... Bg5 is Dutch killer

Try the Ruy Lopez Exchange variation 1.e4 e5 2.Nf3 Nc6 3.Bb5 a6 4.Bxc6

Or play the Italian game 1.e4 e5 2.Nf3 Nc6 3.Bb5 

3.Bb4 for the Italian  

I'm sorry , :) but it's 3.Bc4 not Bb4. 

yes indeed is it  Bc4 

Knowing the openings well helps you to know if your opponent is playing for a draw, a won endgame, etc.

Sorry, I take back what i said before, it is probably the dutch gambit