Context: Green , and ... hot . The tropics , then , for all that she 'd been in an air conditioned bedroom on the Eastern Seaboard not 10 seconds before . She did n't make a sound , and then she heard it . A footstep , behind her .

Question: Why did she hear a footstep behind her ?
Options:
0. Because she was in an air conditioned bedroom .
1. Because she was in the tropics .
2. None of the above choices .
3. Because she was green and hot .
Answer: 2