The C-4 is a mine!!
He plants it, it's his b move you ******* i told you.
And that rocket in a 45º it's his down A
C-4 is not a mine, it's a plastic explosive, which Snake detonates with a remote detonator.
The mine, aka his D-smash, is proximity based, like the motion sensor bomb.
And that pretty much confirms the RPG as his down-tilt.
Also to the guy who said something about Dream Mix... Snake's attack are based on what he does on his games(except the FS, that's from Raiden).
In MGS you could use C-4 to destroy walls and you could even stick it to enemies.