Answer: Option (b) is the correct answer.
Step-by-step explanation:
Electronic configuration of copper is
and copper is known as the best conductor of heat and electricity.
This is because in copper there is availability of free electrons in its valence shell (outermost shell).
And, as it is known that electricity is the flow of electrons. This means that since copper metal contains a number of free electrons. Hence, it can easily conduct electricity.
Thus, we can conclude that copper and some other metals are good conductors because copper atoms have a loosely held free electron in their outer shell that is able to move freely to other atoms.