Final answer:
The comparative form of pretty is prettier and the superlative form is prettiest.
Step-by-step explanation:
The comparative form of the adjective pretty is prettier and the superlative form is prettiest.
For example, you can say, "She is prettier than her sister" to show a comparison between two people. And you can say, "She is the prettiest girl in the class" to show that she is the most beautiful among the group.
Remember, when forming the comparative form, you typically add "-er" to the end of the adjective, and when forming the superlative form, you typically add "-est" to the end of the adjective.