Which Is an Illustration of the Defense Mechanism "Repression

Which is an illustration of the defense mechanism "repression"?

A) Mary witnessed the death of her child but cannot remember it.
B) Mark wants to remember what he ate for lunch but is not sure whether it was tuna or hamburger.
C) Michael tells people he did not cheat in high school but knows it is unTrue.
D) Rachel thought about going to a party, but her mother forced her to stay home.