Answer:
The correct option is C,no entry needed
Explanation:
The $5,000 received as as revenue in advance would have been debited to cash and credited to revenue in advance as a liability,hence as at December 31st of the same year,no single adjusting entry is required since the actual sales of goods did not take place in December.
In January,when sales is expected to have taken place by transferring the goods paid for to the customer,the adjustment in the books of accounts would a credit to sales revenue and a debit to revenue in advance.