The correct explanation for why glass is a good insulator relates to the atomic structure and behavior of its electrons. Glass is primarily an insulator because:
The atoms in glass do not hold on tightly to their negatively charged particles.
This means that glass does not allow electrons to flow freely, which is what is needed for electrical conductivity. Instead, the electrons are bound tightly to the atoms, preventing the free movement that would allow for electrical conduction. Therefore, the third option is the most appropriate.