Q. When an open coiled helical compression spring is subjected to an axial compressive load, the maximum shear stress induced in the wire is (where D = Mean diameter of the spring coil, d = Diameter of the spring wire, K = Wahl's stress factor and W = Axial compressive load on the spring)

• (A) WD πd3 ×K
• (B) 2WD πd3 ×K
• (C) 4WD πd3 ×K
• (D) 8WD πd3 ×K