The displacement time graph of aprticle executive SHM is shown in figure. Which of the following statements is/are true?

At$\mathrm{t}=\frac{\mathrm{T}}{4},\frac{3\mathrm{T}}{4},\dots .$
Velocity is maximum, Hence (a) is wrong.
Hence, acceleration will be maximum at t=0, T/2... Hence (b) is correct.
Since at mean position, force is also equal to zero at that position. Hence force is zero at t=T/4, 3T/4.....  Hence (c) is correct.
At t=T/2, KE at this instant is equal to zero. Therefore, whole of the oscillation energy, at this instant, is in the form of potential energy. Hence (d) is also correct.