Which of the following pronouns can take either the singular form or the plural form depending on the antecedent

Indefinite pronouns can either be in singular form or plural form depending on its context. Although some plurals are independent in reference to antecedents, pronouns either singular or plural must agree with the antecedents.

The answer is beneficial.

They taste good and have different flavorsthey also can be very good for when ur teeth hurt