On September 1, Crane purchased $40400 of inventory items on credit with the terms 1/15, net 30, FOB destination. Freight charges were $820. Payment for the purchase was made on September 18. Assuming Crane uses the perpetual inventory system and the net method of accounting for purchase discounts, what amount is recorded as the liability from this purchase?

a. $41220.

b. $40816.

c. $40400.

d. $39996.