Cooper makes a good conductor because it is made up of very stable atoms

First, and foremost, copper is a good conductor because it is the least expensive of all conductors. What actually makes it a good conductor, however, is how some of its electrons are easily detached. When the outer electrons detach, it allows for a chain reaction of electrons.

The chain reaction is created by one electron moving through a circuit, which in turn makes each electron, in the circuit detach (i.e. chain reaction). As each electron is detached, electricity is allowed to function. Since copper’s electrons detach easier than most other conductors, electricity easily functions through a copper circuit. This is what really makes copper such a good conductor.

The correct answer to go in the blank would be a) complement.