Right answer is (a) (Avgfy/√3 γm0)+(0.9Atnfu/γm1)
To explain: The block shear strength at an end connection for shear yield and tension fracture is given by Tdb1 = (Avgfy/√3 γm0)+(0.9Atnfu/γm1), where Avg = minimum gross area in shear along line of action of force, Atn = minimum net area of cross section in tension from hole to toe of angle or last row of bolts in plates perpendicular to line of force, fy and fu are yield and ultimate stress of material respectively, γm1 = 1.25, γm0 = 1.10.