If the strain energy stored per unit volume in a hollow shaft subjected to a pure torque when t attains maximum shear stress fs is (17 fs)/(64 N), the ratio of the inner diameter to outer diameter is

A

$$\frac{1}{2}$$

B

$$\frac{1}{3}$$

C

$$\frac{1}{4}$$

D

$$\frac{1}{5}$$