Answer: Option (c) is the correct answer.
Step-by-step explanation:
Substances or material that does not allow passage of heat, electricity, light, or sound through them are known as insulators.
For a substance or material to conduct heat and electricity, it must have free electrons that can easily move from one place to another.
Hence, in plastics there are no free electrons and that is why plastics do conduct electricity.
Thus, we can conclude that materials like plastics do not have any loosely bound electrons in their outer shell making it difficult, if not impossible, for electrons to move between atoms.