Madalynn Inc. entered into an agreement with a customer on July 1 to provide accounting services starting immediately. Madalynn Inc. charges $750 a month for these services, and the customer agrees to pay Madalynn Inc. on the 1st of each month for the past month's work, starting August 1. What adjusting journal entry is required by Madalynn Inc. on July 31?

Dr. Accounts Receivable 750; Cr. Service Revenue 750

Dr. Accounts Receivable 750; Cr. Cash 750

Dr. Cash 750; Cr. Service Revenue 750

Dr. Cash 750; Cr. Accounts Receivable 750