Mr. and Mrs. Alvin Charak took a foster child, Robert, into their home in 2015. A state welfare agency paid the Charaks $3,900 during the year for related expenses. Actual expenses incurred by the Charaks during 2015 in caring for Robert amounted to $3,000. The remaining $900 was spent by the Charaks in 2015 towards their own personal expenses. How much of the foster child payments is taxable income to the Charaks in 2015?
a. $0
b. $900
c. $2,900
d. $3,900
Answer: A