Which of the Following Is an Example of a Kickback

Which of the following is an example of a kickback?

A) Barry slips the receptionist $20 so he can get an interview with her boss.
B) Lori buys the purchasing agent of Lincoln Electrical Company an extravagant lunch to cement their friendship.
C) Payton shares industrial secrets with one of his competitors.
D) Chantal pays a department store buyer five percent of all the orders placed by the store.
E) Andrew pays a government official $200 to speed up the licensing process.