Question

A straight conductor carries a current.assume that all free electrons in conductor move with same drift velocity 'v'.A and B are two observers on straight line parallel to conductor.A is stationary and b is moving along line in direction of flow of e with speed 'v',then
a)Both observe magnetic field
b)A observes mag field but B doesn't
c)A and B observe mag field of same magnitude but opp. directions
d)Both do not observe elec field