If the Poverty Line Is $16,000 for a Family of Four

If the poverty line is $16,000 for a family of four and the U.S. has 100 million such families, with 25 million of these families having incomes of $12,000 and 75 million having incomes of $20,000. This means the poverty gap would be

A) zero, because the income numbers average out at $16,000.
B) negative, because there are more above the poverty line than below it.
C) $100 billion, because there are 25 million families $4000 below the poverty line.
D) $400 billion, because there are 100 million families and many are $4000 below the poverty line.