31. Two objects, A and B, initially at rest, are "exploded" apart by the release of a coiled spring that was compressed between them. As they move apart, the velocity of object A is 5m/s and the velocity of object B is −2m/s. The ratio of the mass of object A to the mass object B,ma/mb is
(A) 4/25
(B) 2/5
(C) 5/2
(D) 25/4
