For a sine wave passing through a medium, let y be the displacement of a particle, v be its velocity and a be its acceleration :-
A. `y,v` and `a` are always in the same phase.
B. `y` and `a` are always in opposite phase.
C. Phase different between `y` and `v` is `pi//2`.
D. Phase different between `v` and `a` is `pi//2`
