Ride! Company, a calendar-year company, sells subscriptions to a bicycling magazine to mountain bicycle enthusiasts. The magazine is published semiannually and is shipped to subscribers on April 15 and October 15. Only one-year subscriptions (for two issues) are accepted. Subscriptions received after the March 31 and September 30 cutoff dates are held for the following publication. Cash is received evenly during the year and is credited to deferred subscription revenue. During 2010, $7,200,000 of cash was received from customers. The beginning 2010 balance in deferred subscription revenue was $1,500,000. What is Ride!s December 31, 2010, deferred subscription revenue balance?

a. $5,400,000 b. $3,600,000 c. $3,300,000 d. $1,800,000