Carson went to a merchandisers' market on November 16th and purchased 20 drills at $125 each. The terms of payment of the invoice were 2% 15, Net 30. When he returned to his office on November 20th, he wrote out and mailed a check to pay the invoice. $50 will be recorded in his:
A. Purchases account
B. Sales account
C. Purchases discount account
D. Sales discount account