Question

What made Jake suspicious about the man with the camera?
he was wearing dark glasses
he took a photo of them
he was the same man who sold Jake the map
he had followed them all day

Answer 1

I don’t have the story text — which passage is this from? If you want a quick answer without more context, the option that most clearly makes Jake suspicious is: "he had followed them all day" — following someone is direct evidence of being watched and usually the most worrying.