Classify the following items as (1) accrued revenue, (2) accrued expense, (3) unearned revenue, or (4) prepaid expense:

Line Item Description	Classification
a. Cash paid for rent of office space	Accrued expenseAccrued revenuePrepaid expenseUnearned revenue
b. Fees received for services to be performed	Accrued expenseAccrued revenuePrepaid expenseUnearned revenue
c. Wages owed but not yet paid	Accrued expenseAccrued revenuePrepaid expenseUnearned revenue
d. Services rendered for cash to be received	Accrued expenseAccrued revenuePrepaid expenseUnearned revenue