Which of the following transfers would result in a gift tax?

Select one:

a. Bob gifts $11,000 to his daughter Barbie.

b. Elroy gifts $50,000 to his wife, Elizabeth, who is a U.S. citizen.

c. Adam gives his favorite employee, Aaron, a new car at Aaron's retirement worth $20,000.

d. Pete transfers $20,000 to his ex-wife, Patricia. Pete and Patricia were divorced five years ago.