Which of the Following Is an Example of the Phenomenon

Which of the following is an example of the phenomenon known as "operant control" of pain behaviour?

A) Kim is recovering from a broken leg.Although she is walking on crutches, she has been trying to be as independent as possible.
B) Janet had to have a finger amputated after it was partially severed in a slicing accident.Since she feels discomfort in the missing finger, she has been diagnosed with phantom limb pain.
C) Kate's family has always been critical and demanding.However, since her accident, family members have become caring and sympathetic.
D) Mary suffers from chronic back pain.However, she rarely complains to others about the pain and tries to keep her facial expressions from showing that she is in pain.Recently, her doctor reduced her pain medication.