The polar modulus for a solid shaft of diameter (D) is
A
$$\frac{{\pi {{\text{D}}^2}}}{4}$$
B
$$\frac{{\pi {{\text{D}}^3}}}{{16}}$$
C
$$\frac{{\pi {{\text{D}}^3}}}{{32}}$$
D
$$\frac{{\pi {{\text{D}}^4}}}{{64}}$$
Correct Answer: $$\frac{{\pi {{\text{D}}^3}}}{{16}}$$