Help settle the roommate dispute by choosing the correct word.

"Hey! You ate the last slice of pepperoni pizza! I bought it yesterday, so that slice was ___!"

The correct answer is mine.

We use the possessive pronoun mine to replace a noun phrase (like "my slice") so we don't have to repeat it. "My" is a possessive adjective and must be followed by a noun (e.g., "my slice").