Answer:
B. In considering our costs, we need to include what we could have earned by working at part-time jobs instead.
Step-by-step explanation:
When the group of college students include, in their analysis of costs, what they could have earned by working at part-time jobs instead, they are including the opportunity cost.
The opportunity cost is what is given up to do something: the cost of not choosing an alternative.
Including opportunity costs in their cost-benefit analysis reveals sound economic thinking.