Answer:
Debit : Rent in Advance $4,000
Credit : Rent Income $4,000
Explanation:
When Rent was paid in advance :
Debit : Cash $12,000
Credit : Rent in Advance $12,000
The required adjusting entry on December 31, 2020 :
Debit : Rent in Advance $4,000
Credit : Rent Income $4,000