San Jose Corporation Uses the Perpetual Inventory Method

San Jose Corporation uses the perpetual inventory method. On March 1, it purchased $90,000 of merchandise inventory, terms 2/10, n/30. On March 3, San Jose returned goods (not damaged) that cost $9,000.
On March 9, San Jose paid the supplier. On March 9, San Jose should credit:

A) Purchase discounts for $1,800
B) Inventory for $1,800
C) Purchase discounts for $1,620
D) Inventory for $1,620