Context: So we ran back , and then started walking again when we were near the entrance and the mosquitos lessened . We talked and watched the lake next to us . A train went by to our other side , slightly obscured by the trees , and we waved as it passed .

Question: Why did they run back ?
Options:
0. None of the above choices .
1. So they could leave the park .
2. To get away from the mosquitos .
3. To catch up with the train .
Answer: 2