When electrons are added to the outermost shell of a carbon atom, it forms

When electrons are added to the outermost shell of a carbon atom, it forms anion that has a larger radius.

Explanation:

Electron affinity is the change in energy when a neutral atom in its gaseous form gains an electron to form a negative ion. For example, when a neutral fluorine atom in its gas state gains an electron, it releases energy to form a fluoride ion.

the answer is b.) hydrogen bonds between bases.