The Browning Company, which uses perpetual inventory system, reports inventory information for 2020:

January 1 Inventory on hand 4,000 units @$5.50 each.

January 10 Sale 2,000 units @$20.00 each.

January 17 Purchase 1,000 units @$6.00 each.

March 22 Purchase 3,000 units @$7.00 each.

April 15 Sale 1,500 units @$25.00 each.

October 15 Purchase 3,000 units @$7.50 each.

November 20 Sale 3,000 units @30.00 each.

What is the average cost of inventory after January 17 purchase?

A) $6.33

B) $5.67

C) $6.80

D) $6.57