Which scenario is an example of a moral dilemma?

a. a man finds a wallet and must decide whether to return it or use the money to pay for his wife’s lifesaving surgery.
b. a boy needs to decide whether to go to a local college and major in aeronautics or into the military as a foot soldier.
c. a student must choose between taking an introduction to art class or a class on child psychology.
d. a woman must decide if she will stay in her hometown with her friends and family or move far away.