At the end of May 2021, China Trade Ltd has performed $800 of services for a customer on a long term job. The job is expected to be completed in July 2021, at which point the customer will be sent an invoice requesting payment. The adjusting entry required at the 31st May 2021 is: Select one: a. Debit Service Revenue $800 Credit Accrued Revenue $800 O b. Debit Unearned Revenue $800 Credit Service Revenue $800 c. Debit Accrued Revenue $800 Credit Service Revenue $800 O d. Debit Cash at Bank $800 Credit Service Revenue $800