Answer: d) all of these effects
Explanation:
This situation describes all of the above effects.
Out-group homogeneity effect is the tendency to describe everyone that is not in your group to be a certain way while people in your group are different which is the case here with Jackson's group thinking that all downhill skiers are destroyers.
In-group bias is also present here as it involves the favoring of one's group over others which Jackson does with his club and there is also stereotyping as there is a general belief about all the downhill skiers simply because they are downhill skiers.