Hasty generalizations are conclusions that are not logically justified by sufficient evidence. In this case, you answer would be A, "she's wearing a green shirt, so green must be her favorite color". You can't assume that someone's favourite colour is green because one day he woke up and decided to wear a green shirt. Perhaps that one was the only clean shirt the person had.
You could not say that B is hasty generalization because for someone to be on the ski team they should know how to ski, so there is little evidence to think that. In C, the person talking about his dog knows him/her so, despite the fact that he does not know all the dogs in the world, he can talk about his. Finally, sometimes mayonnaise is made with anchovies so it is kind of logical to think that if you like mayonnaise, you will like anchovies.
