Question: John's took his appointment book with him to a checkup but couldn't find it anywhere. He looked and he looked but he didn't know where it was.  It wasn't until he bought a new one, went home, took a shower that he found it.  Where was it?

Choices: 
- office supply store
- wallet
- doctor's office
- handbag
- pocket

The rationale to choose "pocket" as the answer is that: 

rivers flow trough valleys.