Answer:
stereotype; prejudice
Explanation:
Selena has an idea of what a computer programmer is like. She believes them to be antisocial and boring. However, this is a stereotype, or an over-generalization about a particular category of people. Therefore, it does not actually reflect what all individuals in this group are like. The fact that she does not like Mark is an example of prejudice, as she is basing her conclusion on a preconceived idea she has of him, without taking the time to actually get to know him.