Final answer:
Rent received in December 2018 for January 2019 is accounted as a liability for the leasing company as it is unearned revenue until the rental period occurs in January 2019.
Step-by-step explanation:
If an apartment leasing company receives the rent for January 2019 from a tenant in December 2018, this will be reported by the leasing company as b. A liability in 2018. According to the principles of accrual accounting, revenues should be recognized in the period in which they are earned, regardless of when the cash is received.
Since the rent is for January 2019, it is not earned in December 2018. Therefore, the payment received in advance is recorded as a liability, specifically as unearned revenue or deferred revenue, and will be recognized as revenue only in January 2019, when the rent period actually occurs.