The correct answer is (C) To dress up (with fussy, painstaking care); to primp; to dress oneself carefully or smartly; to make trim in appearance. Also, (of animals, especially birds) to trim, smooth, or clean the feathers with the beak or tongue. Finally, to congratulate oneself mildly.

Preen comes from Middle English preynen (to prune).

Examples of use:

• While I reached for my camera, the peacock preened itself.
• She preened before the mirror while he waited in the living room.