Which word is the indefinite pronoun in this sentence?

mrs. ortiz wondered whether both her daughters would like to take a trip to the grand canyon.

The answer is "both". Its a plural indefinite pronoun.

beethoven's first public performance in vienna was on march 29, 1795. he gave a piano concert, or akademie, in vienna's burgtheater as part of an event organized by joseph haydn (probably op. 15). in these early years, beethoven's success as a composer was closely tied to his career and renown as a piano virtuoso.

explanation:

your answer would be d.)