Please Help. I am amending my Missouri state return because of the unemployment tax break. TurboTax has me reviewing the MO-1040 form. It is here I am not sure what to do

It has me reviewing information on the Mo-1040 and is asking me in question 43 to "indicate reason for amending"? It has suggested letter A, which is "Federal Audit. Enter date of IRS report" but I'm not sure about that and I don't know the date. I'm just amending to get my tax cut for unemployment. B and C I don't think apply to me. D says "Correction other than A, B, or C. Enter date of federal amended return, if filed" Please help