Which of the Following Is an Example of the Make-Or-Buy

Which of the following is an example of the make-or-buy decision?

A) A textbook maker decides whether to rent an office building or buy an office building.
B) A shoe salesman decides whether to work at a department store or a local shoe store.
C) A mother decides whether to babysit her own children or send her children to daycare.
D) A scientist decides whether to hire a new research assistant or give the research assistant he already has employed more work.
E) A teacher decides whether to teach first or second grade.