Which One of the Following Transactions in a Particular Year

Which one of the following transactions in a particular year is included in gross domestic product for that year?

A) Social Security payments to retirees
B) The government pays a computer services company that assisted in the delivery of Social Security payments to retirees.
C) A car is produced in the previous year and remains in inventory for the entire year under consideration.
D) A stay-at-home parent performs housework that the family would otherwise have paid a maid $20,000 a year to perform.