Alegendary equestrian vaulter is sitting behind you.
determine the case and function of the underlined pronoun.
objective; indirect object
possessive; adjective
nominative; subject
objective; object of preposition

You couldn't mark the underlined pronoun here, but there is only one pronoun anyway: "You".

You here is the object of the sentence, and the subject is "a legendary equestrian".

However, the full object is "behind you": so the correct answer is objective; object of preposition .

The preposition here is "behind"