Which of the following statements concerning the credit for child and dependent care expenses is not correct for 2021? Oa. A taxpayer is not allowed both a deduction as a medical expense and the credit for child and dependent care expenses on the same amount. Ob. A taxpayer is not allowed both an exclusion from income and the credit for child and dependent care expenses on the same amount. Oc. If a taxpayer is a full-time student with no earned income, no credit for child and dependent care expenses can be claimed. Od. If a taxpayer's adjusted gross income is $123,000, the rate for the credit for child and dependent care expenses is 50%.