Answer: Since there are only two plates shown, the bolts are in single shear. The available bolt strength for A325 bolts at the strength limit state is dependent on if the threads are in the shear plane or not. It is conservative to assume that they are if it is not explicitly stated in the problem. Thus, assume the threads are in the shear plane. The shear force per bolt is then:
Vbolt = 230 kip / 11 bolts = 20.9 kips. The required bolt size for this shear strength is 21.6 kips per bolt for a 7/8" section. Note-the problem did not use the 1" thickness.
The answer is C) 7/8-in. bolt