Which piece of evidence would most strongly support the thrifty gene hypothesis at a population level?

• A. Consistent associations across multiple populations showing alleles that increase energy storage were positively selected during historical famines and now increase obesity risk in calorie-rich environments
• B. Laboratory demonstrations that fasting for 24 hours increases appetite in healthy volunteers
• C. Observations that portion sizes increased in the past 50 years and processed foods are cheaper in one country
• D. A single case report of rapid weight gain in an individual who migrated from a food-scarce region to a food-abundant country

Answer: (A)