Choose the correct item

1. Her cheek had a nervous
   [response|twitch] when she was talking.
2. He's as good as a lie
   [finder|detector] and can tell who is not telling the truth in an interview.
3. His face suddenly turned bright red; it was a tell tale
   [signal|sign] he was lying.
4. People can't control muscle
   [spasms|flashes].
5. She was so nervous that she tried to
   [hide|conceal] behind the books in her hands.
6. The most important thing is to trust your
   [nature|instincts] when dealing with people.