Allie and Buddy are married, file a joint return, and have one son, Zack, age 5. Buddy has earned income of $47,000 and Allie was a full-time student for 8 months (with no income). They paid a qualified child care center $3,450. How much is Allie and Buddy’s child and dependent care credit for the year?

a. $0.

b. $400.

c. $420.

d. $690.