4.Block A, with a mass of 10 kg, rests on a 30* incline. The coefficient of kinetic friction is 0.20. The attached string is parallel to the incline and passes over a massless, frictionless pulley at the top. Block B, with a mass of 8.0 kg, is attached to the dangling end of the string (take √3 1.7 and g =10 m/s2). The acceleration of B is: (A) 0.72 m/s2, up (B) 0.72 m/s2, down (C) 2.6 m/s2, , up (D) 2.6 m/s2, down (E) 0 m/s2