Select the sentence with a clause used as a modifier to the subject. The boy who arrived here Tuesday was running late. We left the diner late because we saw some old friends. The reason she bought those shoes was that her friend told her to.

Ans is: "We left the performance early because we were tired." The sentence with a clause used as a modifier to the subject. The clause 'because we were tired' stands as the modifier for the subject, we. It gives the reason why they left early.