Which of the following statements are correct ? <br> (a) Centre of mass of a body always coincides with the centre of gravity of the body. <br> (b) Centre of mass of a body is the point at which the total gravitational torque on the body is zero. <br> (c) A couple on a body produce both translational and rotational motion in a body <br> (d) Mechanical advantage greater than one means that small effort can be used to lift a large load.

Question

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