On December 31, the end of the accounting period, $21,200 in service fees had been earned but not billed or received. The Wesleyan Company uses the account Fees Receivable to reflect amounts due but not yet billed. The proper adjusting entry would be:

Select one: a. Unearned Service Fees 21,200 Service Fees Earned 21,200 b. Fees Receivable 21,200 Unearned Service Fees 21,200 c. Cash 21,200 Service Fees Earned 21,200 d. Fees Receivable 21,200 Service Fees Earned 21,200