please explain

Indicate which journal entry must be recorded for the following economic event on the exact day of the event: January 30^th. Received a deposit of $800 for servicing a mid-afternoon get together on February 29^th. The group wanted to reserve the date to do something special in her house as it only happens once every 4 years.

Multiple Choice

a. Dr Cash $800 Cr Advances from customers $800

b. Dr Cash $800 Cr Revenue $800

c. Dr Account Receivable $800 Cr Unearned Revenue

d. No journal entry

e. None of the other alternatives are correct