what is the difference between alternating current and direct current?

Question

a direct current requires insulators, but alternating current does not
b alternating current requires insulators, but direct current does not
c alternating current regularly, reverses direction, direct current flows, and only One Direction
d alternating current flows, and only One Direction direct current regularly reverses direction

Answer 1

c) alternating current regularly reverses direction, while direct current only flows in one direction.