How might the history of Europeans in the Americas
have been different if the Indians had
not been killed by European diseases?

The answer is option b and c.

1) which is an example of active listening during a formal discussion the answer is d. responding to questions this proves that you were actively listening to the conversation being held in the discussion and that you also know about the topic being discussed2) finding the right balance in a formal discussion is primarily the answer is a. being activeyou want to actively take part of the discussion and prove that you are focused. able to understand what others are saying and make your own input