Deferred Revenue, which represents the company's obligation to honor gift cards previously issued to customers, totaled $6,600 at the beginning of the year and $9,000 at the end of the year. Customers purchased gift cards amounting to $50,400 during the year. What was the amount of gift cards redeemed by customers during the year?

$48,000

$52,800

$66,000

$34,800