Which statement is a proposition?
she set sail on tuesday.
why are you late?
good afternoon!
what happened to my sandwich?

The correct answer is A. She set sail on Tuesday.

Explanation:

A proposition is a sentence or statement that can be true or not and that expresses an opinion, judgment or declaration about something, which means a proposition expresses how something happened or should happen, because of this proposition are declarative sentences that mean propositions do not include questions, commands or expression of emotions and thus, they end with a period. Considering this, the statement that is a proposition is A. "She set sail on Tuesday" because this statement proposes how something happened, is a declarative sentence and is not a question or exclamation.

themselves

an intensive pronoun is a pronoun that ends in self or selves, such as himself, herself, themselves, yourself, ourselves. since band members is a third person plural, the correct intensive pronoun would be themselves. if the band was talked about as a collective noun, itself would be the appropriate intensive pronoun. intensive pronouns are used to add emphasis to the noun it's modifying which is why it directly follows it.

banquo is a great foil