Which of following statements are correct ? ltbgt (a) Centre of mass of a body always coincides with the centre of gravity of the body
(b) Central of mass of a body is the point at which the total gravitational torque on the body is zero
(c ) Couple on a body produces both translational and rotation motion in a body
(d) Mechanical advantage greater than one means that small efforts can be used to lift a large load

Options

A. (b) and (d)
B. (a) and (b)
C. (b) and (c)
D. (c) and (d)