Answer:
The central Idea is "For many reasons, notable people sometimes avoid revealing their private identity".
Explanation:
If you read the text the author clearly expresses his/her feeling based on that one topic. The main idea is implied. (are those multiple answers or a text I'm not sure)
D) Recruiter.
On top of that, "experience in recruiting" basically gives it away. <span />
In relating to behavior, normal means ordinary. Someone who displays normal (and usually healthy) behavior like the majority of people. Abnormal behavior is just the opposite.
For example: Person A sees a poisonous snake. They get away from the snake in fear. This person has normal behavior. Person B sees the same snake. They get on the ground and play with the snake. This person has abnormal behavior.