Assume a retail tenant is paying a base rent of $180,000 per year (or $15,000 per month). In addition, the tenant must pay 7.5 percent of gross store sales in excess of $200,000 per month as percentage rent. If the store produces $280,000 in gross sales in a month, what is the total rent due for the month?

A. $6,000

B. $13,500

C. $15,000

D. $21,000