Carolyn is unmarried and has one dependent child, age 6, who lived with her for the entire year. In 2019, she has income of $16,000 in wages and $6,000 of unearned income (none of which was "disqualified income"). Her AGI is $22,000.

a. What is Carolyn's tentative earned income credit (before phaseout)?

b. What is Carolyn's allowable earned income credit?

c. If Carolyn has no income tax liability (before the earned income credit is subtracted), is she entitled to a refund in the current year?

d. How will your answers to Parts a and b change if Carolyn is married filing a joint return?