It's B. The dashes separate a mild afterthought.
Answer:
Scent
Explanation:
The other three words have a negative connotation, and scent does not.
Knowing about a danger and bravery are connected because in both you are knowing about the danger, when you are brave you will face the danger that you know about, if you just know about the danger you don’t have to be brave however. But if you know about danger and go for it anyways you are brave to do so. (Sorry if this doesn’t help)