Two parallel current-carrying wires with current in the same direction.

Answer: Option D

Think of the lovers analogy. When both currents are in the same direction, it’s like couple in love, so attraction. Likewise, when the currents are in opposite direction, they quarrel, hence repulsion.

On the magnitude of the force, always remember for electric force, magnetic force or gravitational force between objects, the forces are equal and opposite, action-reaction pair (Newton’s 3rd Law).

Two parallel current-carrying wires with current in the same direction. https://youtu.be/cE19DKbmhew