Answer:
A) She and her nephew enjoy an afternoon at the zoo.
Step-by-step explanation:
An opportunity cost are the extra costs incurred or benefits lost from choosing one activity or investment from another alternative.
In this case, Lois has to choose between taking her nephew to the zoo or working on the new project.
If she takes her nephew to the zoo, her opportunity cost will be not being able to work in the new project.
If she decides to work on the new project, her opportunity cost will be not being able to go to the zoo.