Step-by-step explanation:
Good conductors are the conductors through which electric current can pass easily due to the free movement of electrons.
Copper and other metals are good conductors because the electrons in the outermost shell of these elements are held loosely. Therefore, when electricity is passed through copper or other good conductors then electric charges move freely as loosely held electrons come out of the outermost shell easily.
As a result, they tend to flow with the electric charge.
Thus, we can conclude that the statement copper atoms have a loosely held free electron in their outer shell that is able to move freely to other atoms best describes why copper and some other metals are good conductors.