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.