Which of the following taxpayers qualifies to claim the child tax credit: C (a) A taxpayer who files as head of household and claims his 18-year-old daughter as a dependent (she's a full-time student). (b) A divorced taxpayer who claims his 15-year-old son as a dependent. The son C lives most of the year with the taxpayer's former spouse. The taxpayer was given the dependency exemption when the former spouse signed away their right to the exemption. C (c) A 25-year-old unmarried taxpayer who claims her 10-year-old sister as a dependent. " both (b) and (C) both (a) and (b)