What Fundamental Fact Underlies the Operation of Essentially All Electric

What fundamental fact underlies the operation of essentially all electric motors?

A) Alternating current and direct current are both capable of doing work.
B) A magnetic North pole carries a positive electric charge, and a magnetic South pole carries a negative electric charge.
C) Iron is the only element that is magnetic.
D) A current-carrying conductor placed perpendicular to a magnetic field will experience a force.
E) Opposite electric charges attract and like charges repel.