Seven-Year Old Pat Does Not Like to Eat Broccoli and Does

Seven-year old Pat does not like to eat broccoli and does not like to clean his room. Pat's mother tells him that if he eats all his broccoli at dinner tonight then he will not have to clean his room tonight. In her effort to have Pat eat broccoli, Pat's mother is attempting to apply the process of:

A) behaviour modification through shaping.
B) response cost learning.
C) operant extinction.
D) negative reinforcement.