Answer:
The best definition of "casual" considering the context would be 1. Relaxed and unconcerned.
Step-by-step explanation:
This would be the best definition precisely because of the question she asked the kid considering the kid´s previous and aggressive behavior. He was clearly dealing with what the teacher said about "not to take the name of the Lord in vain" and the mother (we are guessing that the mother was the one who asked the question) had to act as relaxed as possible to alleviate the situation.