Final answer:
The opportunity cost for Steven choosing to watch a movie over doing his economics assignment is the lower score he may receive on the assignment since that is the valuable alternative he gives up.
Step-by-step explanation:
The opportunity cost of spending two hours watching a movie instead of completing an assignment in economics for Steven is the value of the next best alternative that he foregoes, which in this case is the economics assignment. Specifically, the opportunity cost for Steven is a) lower score in the economics assignment, because that is what he would sacrifice in order to enjoy the movie. The enjoyment of the movie, time spent on the assignment, or time spent watching the movie are not the opportunity costs, but rather the actual choice or the alternatives being considered.
Opportunity cost is a fundamental principle in economics, reflecting the most desirable alternative given up when a choice is made. Every decision has an opportunity cost, and this cost varies from person to person based on their individual preferences and the alternatives available to them.