On 1 July 2020, Canada Ltd rented out part of an office block. Canada Ltd received $18 000 in advance for a nine-month period. The receipt was credited to a liability account. On 31 December 2020, Canada Ltd's year-end, which of the following adjusting journal entries should be made? Select one:

a. DR Rent income $6 000; CR Unearned rent income $6 000

b. DR Rent receivable $12 000; CR Rent income $12 000 DR Rent receivable $12 000; CR Rent income $12 000 DR Rent receivable $12 000; CR Rent income $12 000

c. DR Unearned rent income $12 000; CR Rent income $12 000

d. DR Cash $12 000; CR Rent income $12 000