The adjective "bonitas" is feminine plural. Therefore, we need to select the nouns that are also feminine and plural.
Here are the options:
- los hombres (masculine plural) - does not agree
- la estudiante (feminine singular) - does not agree
- el profesor (masculine singular) - does not agree
- mis hermanas (feminine plural) - agrees
- los gatos (masculine plural) - does not agree
- mi tío (masculine singular) - does not agree
The only correct answer that agrees with "bonitas" is:
- mis hermanas