A conductro `AB` carrying current `i` is placed vertically above and parallel to a long horizontal conductor `XY` carrying current `I`. Assume that `AB` is free to move and that the wires through which currents enter and leave it do no exert any forces on it. If `AB` is in equilibrium
A. `i=I`
B. `i` and `I` must flow in the same directiion
C. the equilibrum of `AB` is usntable
D. if `AB` is given a small vertical displacement it will undergo oscillations
