Which word could best replace either of the underlined words in the paragraph?

Whenever Colleen goes to the grocery store, she buys food by (((impulse)). She usually doesn’t have a list of things she needs, and she doesn’t plan her meals ahead of time. Her only ((motive)) is to fill her cart with whatever she’d like to eat right then. She usually goes to the store hungry, so she always buys more than she really needs.

A.
desire

B.
hunger

C.
plan

D.
opportunity