A Brass Rod of Length L = 0 $3.5^{\circ}$ the Allowable Shear
Strain in the Copper Is 0

A brass rod of length L = 0.75 m is twisted by torques T until the angle of rotation between the ends of the rod is 3.5 $3.5^{\circ}$ . The allowable shear
Strain in the copper is 0.0005 rad. The maximum permissible diameter of
The rod is approximately: (A) $6.5 \mathrm{~mm}$
(B) $8.6 \mathrm{~mm}$
(C) $9.7 \mathrm{~mm}$
(D) $12.3 \mathrm{~mm}$