The correct answer is A: stereotype.
According to the dictionary a stereotype is a set of ideas that someone may have about a particular type of people, and these ideas are usually wrong or incorrect assumptions about these group of people.
The other options are not possible for the following reasons:
First, Episode refers to a single event or a group of related events. Desolation refers to a place that is completely empty and where everything has been destroyed. Finally, Blunder refers to a serious mistake usually caused by a person who has not been careful.