A Stepped Steel Shaft with Diameters $d_{1}=56 \mathrm{~mm} \text { and } d_{2}=52 \mathrm{~mm}$

A stepped steel shaft with diameters $d_{1}=56 \mathrm{~mm} \text { and } d_{2}=52 \mathrm{~mm}$ is twisted by torques $T_{1}=3.5 \mathrm{kN} \cdot \mathrm{m}$ and $T_{2}=1.5 \mathrm{kN} \cdot \mathrm{m}$ acting in opposite directions. The maximum shear stress is approximately: (A) $54 \mathrm{MPa}$
(B) $58 \mathrm{MPa}$
(C) $62 \mathrm{MPa}$
(D) $79 \mathrm{MPa}$