Rex and Dena are married and have two children, Michelle (age 7) and Nancy (age 5). During 2016, Rex earned a salary of $24,500, received interest income of $300, and filed a joint income tax return with Dena. Dena had $0 gross income. Their earned income credit for the year is:
a. $0.
b. $5,222.
c. $5,412.
d. $5,572.