Why is a friendly refusal preferable?

Because a friendly refusal does not diminish the self-esteem of those who propose something.

Explanation:

A friendly refusal is made in a simple and gentle way, without destroying anyone's self-esteem and showing reasons that allow this refusal to be made. This all maintains respect, understanding and well-being, both for those who proposed something and for those who refused. In this way we can say that a friendly refusal is preferable, because it does not create an uncomfortable situation.

it is the background information on the characters and setting explained at the beginning of the story. the exposition will often have information about events that happened before the story began. the exposition is often the very first part of the plot.