Particle One of Mass M Initially Moves to the Right

Multiple Choice

Particle one of mass m initially moves to the right at v.Particle two of mass 3m is initially at rest.After they undergo an elastic collision,particle one moves directly down.In what direction does particle two move relative to the initial direction of particle one?

A) 63^o
B) 60^o
C) 35^o
D) 30^o
E) 26^o