They appear to be correct
Its the third one.
....................................
1. He approaches a clearing in the woods, Bilbo sees three huge trolls sitting around a fire, eating mutton
2. The trolls threw sacks over each dwarf that approached.
3. Gandalf saved them by throwing his voice to mislead the dwarves and keep the trolls arguing until the morning.
4. They found weapons and took them.
D: Anaphora is the answer
