PE 3-2A Type of adjustment

Classify the following items as (1) prepaid expense, (2) unearned revenue, (3) accrued
revenue, or (4) accrued expense.
a. Cash received for services not yet rendered
b. Insurance paid
c. Rent revenue earned but not received
d. Salaries owed but not yet paid

Answer:
a. Unearned revenue
b. Prepaid expense

c. Accrued revenue 

d. Accrued expense