This question I tried to solve by considering the torsional shear and transverse shear and axial loading. But the answer is not clear. But the answers that I got by different trial and error method was 50ksi and around 100 ksi. And according to the question both are wrong. The Options given are 121.5ksi, 50.9ksi, 772.0ksi, 162. I am confused and I tried for 3 days to get the answer to match.
Just for reference I had calculated the stress at D it is 772.0ksi. The hint given is to use the Distortion energy equation.