Percentage of completion Question

The calculation of the income recognized in the third year of a five-year construction contract accounted for using the percentage-of-completion method includes the ratio of: A) costs incurred in year 3 to total billings. B) costs incurred in year 3 to total estimated costs. C) total costs incurred to date to total billings to date. D) total costs incurred to total estimated cost.

b you recognize revenue each year

those were my thoughts too… Answer is d apparently (question from schweser Q bank)