Sorry for "the clutter" but... I don't find the multiple choice test that good for this sentence (the one where you don't actually get to read the English translation) because of the so many possible correct answer. Just to name a few:

"Polițiștii au adormit nesupraveghind închisoarea. " = "The police officers fell asleep not overseeing the prison." "Polițiștii au adormit supraveghind-mi/-le/-i închisoarea. " = "The police officers fell asleep overseeing my/their/(his/her) prison."