42

Idk, but I know only 2: queen gambit for white and sicilian defence for black

There are 5,362 possible positions (White's second ply move) or 8,902 total positions after two ply moves each. There are 71,852 possible positions or 197,742 total positions after four moves. There are 809,896 possible positions or 4,897,256 total positions after 5 moves.

Too many to bother to count. Unless you have no life or are bored to death and can't find anything else to do.

First is the good moves, second is the sidelines or sub-moves etc. 

First branch is good moves, second branch is sub-lines and third branch is sub-sub-lines. This can grow exponentially.

lots

alright... no need to swear...

no idea

Forced winning openings there's just one.

Where's spongey when we need him the most? 

who?

lol! XD

yeah of course

it is also a natural number, not like aleph zero or aleph null

dunno

ok

Chess openings branch and transpose, so it's impossible to put a number on it. Some variations are 30 moves deep. At what point is it no longer an opening?

Since it's impossible to know exactly what point in a game switches from opening to the middle game, and from the middle game to the endgame, the question is moot.

It's because at some point in a game, your looking at the board, and calculating middle game tactics, even if you don't realize it. The middle game to the end game is even more ephemeral. Part of the board might look like it's at the end game stage, and another part might still be slugging it out with lots of pieces and ripe for middle game tactics.

Three

This is obviously the correct answer.