This question likely results from entering a Form 1099-R that includes code B in box 7 of the Form 1099-R. A distribution reported with code B is never from a Roth IRA. (TurboTax should never even be asking this question since the code in box 7 already provides the answer.)
Code B or H in box 7 of the Form 1099-R indicates a distribution from a designated Roth account in a qualified retirement plan, not from a Roth IRA. Only code J, T or Q in box 7 indicates a distribution from a Roth IRA.
