The fur gives up protons to the rod. The rod gives up electrons to the air. The fur gains protons from the rod. The rod gains electrons from the fur.
I am hesitating between 4 options to answer the following question, which option should I choose?
Question: Why does a plastic rod have a negative charge after being rubbed with a piece of fur?
Possibilities:
- The fur gives up protons to the rod.
- The rod gives up electrons to the air.
- The fur gains protons from the rod.
- The rod gains electrons from the fur.

The rod gains electrons from the fur.