When the Clinic Nurse Starts to Take the "Air Cast

When the clinic nurse starts to take the "air cast" off the grade 2 sprain,the patient asks why it is being removed as he still has pain.The nurse explains that the cast is removed because:

A) the cast will interfere with adequate circulation.
B) the cast will increase the edema.
C) long-term immobilization can cause permanent disability.
D) another heavier cast will be applied.