XYZ company received an annual service fee of $10,000 from a client and recorded it as Unearned service revenue. The company estimates that it has earned 70% of the total fee during year 2021. What journal entry must be made at December 31, 2021? A. Dr. Cash 7,000 / Cr. Service revenue 7,000 B. Dr. Service expense 7,000 / Cr. Service revenue 7,000 C. Dr. Unearned service revenue 7,000 / Cr. Service revenue 7,000 D. Dr. Accounts receivable 7,000 / Cr. Service revenue 7,000