Which of the following is a requirement for a taxpayer to be eligible to claim the Earned Income Tax Credit (EITC) on their 2021 return? They must:
A. be a U.S. citizen
B. be younger than age 65 at the end of the year
C. file a return using either the single head of household or qualifying widow(er) filing statuses
D. have a valid SSN for employment in the U.S.​