Alex Is a Calendar- Year Sole Proprietor

Alex is a calendar- year sole proprietor. He began business on December 1, this year. He uses the accrual method accounting. Alex had the following collections in December: • Collected $7,000 in December, from clients who paid cash for services to be performed next year.
• Collected $5,000 in December, for services performed during December; deposited in an operating account on December 31, this year.
• Collected $12,000 in December; on accounts receivable for services performed in December; deposited in opera account on January 2, next year.
What is the amount Alex must include in his income for December?

A) $17,000
B) $7,000
C) $12,000
D) $24,000