Fragment Company leased a portion of its store to another company for eight months beginning on October 1, at a monthly rate of $975. Fragment collected the entire $7,800 cash on October 1 and recorded it as unearned revenue. Assuming adjusting entries are only made at year-end, the adjusting entry made on December 31 would be:

a. A debit to Unearned Revenue and a credit to Rent Revenue for $4,875.
b. A debit to Rent Revenue and a credit to Cash for $2,925.
c. A debit to Rent Revenue and a credit to Unearned Revenue for $2,925.
d. A debit to Cash and a credit to Rent Revenue for $7,800.
e. A debit to Unearned Revenue and a credit to Rent Revenue for $2,925.