Answer:
b. Debit Unearned revenues for $400.
Step-by-step explanation:
When money is received in advance for a service that is yet to be rendered, the money is accounted for as a liability called deferred or unearned income.
The entries are
Dr Cash
Cr Deferred revenue
when the service is rendered, revenue is said to be earned with the following entries passed
Dr Deferred revenue
Cr Revenue
Hence when $1,000 for services was received on December 1 and was recorded as a liability
Dr Cash $1,000
Cr Deferred revenue $1,000
when $400 had been earned
Dr Deferred revenue $400
Cr Revenue $400
Option b is right
b. Debit Unearned revenues for $400.