Concept:Two parallel current-carrying conductors exert a magnetic force on each other.Explanation:When currents flow in the same direction in two parallel conductors, their magnetic fields interact.According to the right-hand rule, the conductors experience a force that pulls them toward each other.This happens because the magnetic field produced by one conductor exerts a force on the current in the other conductor.Therefore, conductors carrying currents in the same direction attract each other.Answer:D. attract each other