The correct answer is (c) high strength fatigue
To explain I would say: The advantages of HSFG bolts over bearing type bolts are : (i) joints are rigid, (ii) bolts are not subjected to shearing and bearing stresses as load transfer is mainly due to friction, (iii) high static strength due to high frictional resistance, (iv) high strength fatigue since nuts are prevented from loosening, (v)smaller number of bolts results into smaller number of gusset plates.