Two charged particles traverse identical helical paths in a completely opposite sense in a uniform magnetic field B = `B_0 hatk`
Options:
(a) They have equal z-components of momenta.
(b) They must have equal charges.
(c) They necessarily represent a particle-antiparticle pair.
(d) The charge to mass ratio satisfy : `(e/m)_1+(e/m)_2=0`