Videobusters, Inc. offered books of video rental coupons to its patrons at $40 per book. Each book contained a certain number of coupons for video rentals. During the current period 500 books were sold for $20,000, and this amount was credited to Unearned Rental Revenue. At the end of the period, it was determined that $15,000 worth of coupons had been used by customers to rent videos. The appropriate adjusting entry at the end of the period would be:
a. Debit Rental Revenue $5,000 and credit Unearned Rental Revenue $5,000.
b. Debit Rental Revenue $15,000 and credit Unearned Rental Revenue $15,000.
c. Debit Unearned Rental Revenue $5,000 and credit Rental Revenue $5,000.
d. Debit Unearned Rental Revenue $15,000 and credit Rental Revenue $15,000.