Which example seems most like a formal discussion? a debate between students about a topic from history a chat among a group of friends about their favorite music a phone call between students about their weekend plans a conversation between a mother and son about his grades a debate between students about a topic from history

a debate between students about a topic from history

Explanation:

Conversations of Mothers about grades are hardly formal talk, same goes to weekend plans. Chatting already implies that this is not a formal conversation.

This all is quite different than two students discussing about a period in history, a historical character, or something similar. In this case, the discussion is academic and most likely to be formal than the other situations.

a. theta waves. this is because the person is in a light sleep which means the brain waves would show these kind of waves.

b: to eliminate competition from other farmers