Answer:
Opportunity cost
Step-by-step explanation:
In economics (a social science that studies human behavior in relation to ends and scarce means which have alternative uses), there are basic concepts such as scarcity, scale of preference, opportunity costs etc.
Human wants are unlimited and termed to be insatiable. However, the resources available to satisfy these wants are unlimited hence these wants are grouped in the order of importance known as a scale of preference. As the available resources are used to meet a need or satisfy a want, another will go unsatisfied due to the limited resources available.
The need/want that goes unsatisfied is known as the opportunity or real cost or cost of the alternative forgone. This is what Jacks salary will be considered as if he quits his job.