Stabilizing selection... I think it might be right if I'm wrong, sorry if I am.
A 'Trend' is a large social influence if this is what you are talking about. Trends are something where one person does/wears it (usually a popular person everyone likes) and then everyone else starts doing it.
Exceeding expectations mean going above and beyond. If your teacher says to explain, the. Use as much details and insight as you can. Go a step above.
