Two identical particles, cach of rest mass m, colide and produce an produce an extra particle- antiparticle pair of same mass. if one of the particies is at res

Two identical particles, cach of rest mass m, colide and produce an produce an extra particle- antiparticle pair of same mass. If one of the particies is at rest then the other must have mininum kinetic energy equal to (1) 2m,cá (2) 4m,c (3) 7m,e (4) 6m,e