One end of a uniform rod of mass M and cross-sectional area A is suspended from a rigid support and an equal mass M is suspended from the other end. The stress at the mid-point of the rod will be
3Mg2A
At the mid-point, stress will develop because of half of the weight of the rod and that of the suspended weight.
Therefore, stress at mid-point is given by Mg+12MgA=3Mg2A, which is choice (b).