Which of the following is an example of an indefinite pronoun?

The example of an indefinite pronoun is "few" because it refers to an unspecified quantity of people or things, rather than a specific one. Indefinite pronouns are used when the exact identity of the noun they replace is not known or is not important. In this case, "few" can represent an unknown number of items or individuals, making it indefinite.

On the other hand, "she" is a personal pronoun that refers specifically to a female individual, "who" is an interrogative pronoun used to ask questions about people, and "this" is a demonstrative pronoun that points to a specific thing or person. Each of these does not fit the definition of an indefinite pronoun, which is why "few" is the correct answer in this context.