The principal advantage of the completed-contract method is that

a. reported revenue is based on final results rather than estimates of unperformed work.

b. it reflects current performance when the period of a contract extends into more than one accounting period.

c. it is not necessary to recognize revenue at the point of sale.

d. a greater amount of gross profit and net income is reported than is the case when the percentage-of-completion method is used.

The correct answer is a. reported revenue is based on final results rather than estimates of unperformed work. Why it is correct and why the others are wrong.