Final answer:
Adoption assistance should be reported in Boxes 1, 3, 5, and 6 on the W-2.
Step-by-step explanation:
For reporting adoption assistance on the W-2, you would enter the amount in Boxes 1, 3, 5, and 6. Box 1 represents wages, tips, and other compensation subject to federal income tax, Box 3 represents Social Security wages, Box 5 represents Medicare wages and tips, and Box 6 represents Medicare tax withheld.
So, the correct answer is option A. Additionally, Box 12 is used to report certain types of compensation, but it is not applicable for reporting adoption assistance.