What is the main reason to do research before a group discussion? to find facts and details to use as evidence to find a topic that is interesting and complex to be able to talk a lot during the conversation to show why a student’s opinion is the only right one

Explanation:

When you're going to assist to a discussion you must talk based on facts and evidence, otherwise you're going to be speculating and that takes you nowhere in the discussion.

In fact, evidence is the main core of discussion. Imagine that a political leader attends to a public discussion and talks about different topics without evidence, he's just a clown to people.

a.   it resulted in widespread unemployment.

2686-2181 bce-- "egyptian civilization developed along the nile river in large part because the river’s annual flooding ensured reliable, rich soil for growing crops."

1069-664 bce-- "ancient egyptians developed wide-reaching trade networks along the nile, in the red sea, and in the near east."