Beth Operates a Plumbing Firm

Beth operates a plumbing firm. In August of last year she signed a contract to provide plumbing services for a renovation. Beth began the work that August and finished the work in December of last year. However, Beth didn't bill the client until January of this year and she didn't receive the payment until March when she received payment in full. When should Beth recognize income under the accrual method of accounting?

A) In August of last year.
B) In December of last year.
C) In January of this year.
D) In April of this year.
E) In March of this year.