challenge: According to Hilary Hoynes' research, what was the impact of the Food Stamp Program on birth weights?
  
  A. A 7% reduction in low birth weights for whites and a 5-11% reduction for blacks
  B. No significant change in birth weights for any demographic group
  C. A 10% increase in low birth weights for whites and a 15% increase for blacks
  D. A 20% increase in birth weights for all demographic groups
  Answer: 