Jose and Maria work at a restaurant. Jose can make either 10 pancakes or 4 waffles; Maria can make either 8 pancakes or 2 waffles. According to this scenario, the opportunity cost of making one waffle for Maria is

The cost of opportunity is 4 pancakes.

Explanation:

The cost of opportunity is by definition the amount of things you don't do or buy, because of choosing doing or buying something else. In this case, Maria can make:

8 pancakes 2 waffles

This means that at every moment, she can choose to make or 8 pancakes or 2 waffles, but not both. If we continue with this logic, in the time she could make 1 waffle, she could have chosen to make 4 pancakes. This is her cost of opportunity.