BPP P&R Kit MCQ- Inventories and biological assets

At 31 March Tentacle had 12,000 units of product W32 in inventory, included at cost of $6 per unit. During April and May 20X7 units of W32 were being sold at a price of $5.40 each, with sales staff receiving a 15% commission on the sales price of the product.

At what amount should inventory of product W32 be recognized in the financial statements of Tentacle as at 31 March 20X7?
(a) $55,080
(b) $72,000
(c) $64,800
(d) $61,200

Answer per BPP:
NRV- (12,000 * (5.4 * 85%)= $55,080

I did use the NRV of $5.40 but I did not minus the sales staff commission.
Why did they minus it? Is that considered to be a cost to make the sale?

Thanks!