It can be seen from the figure that A and B:λ= 100cm = 1m, and T=2s, then the wave velocity V = λ t = 0.5m/s can be seen from the figure B. At the moment of t= 1.0, the velocity direction of particle A is upward, so it is judged that the wave propagates in the positive direction of X axis on the figure A.

C, t= 1s = 0.5t. At the moment shown in the figure, particle A is moving upwards, and the displacement of particle A increases first and then decreases from t=0 to t =1s, so C is correct.

D, t=4s=2T, that is, from the time shown 1T, the particle A vibrates upward through the equilibrium position, so d is wrong.

So choose C.