Which of the Following Statements Regarding IRAs Is False

Which of the following statements regarding IRAs is false?

A) Taxpayers who participate in an employer-sponsored retirement plan may be allowed to make deductible contributions to a traditional IRA.
B) The ability to make deductible contributions to a traditional IRA and nondeductible contributions to a Roth IRA may be subject to phase-out based on modified AGI.
C) A taxpayer may contribute to a traditional IRA in 2021 but deduct the contribution on her 2020 tax return.
D) Taxpayers who have made nondeductible contributions to a traditional IRA are taxed on the full proceeds when they receive distributions from the IRA.