If a particle slides back and forth between two smooth planes as shown in figure then correct statement is

a) The motion is oscillatory 

b) The motion is SHM
c) If h is the initial height, then its period $\mathrm{T}=\frac{4}{\sin \mathrm{\theta }}\sqrt{\frac{2\mathrm{h}}{\mathrm{g}}}$

d) If h is the height , then its period $\mathrm{T}=\frac{2}{\sin \mathrm{\theta }}\sqrt{\frac{2\mathrm{h}}{\mathrm{g}}}$