Which factor is most strongly associated with variations in life expectancy across populations?

• A. Diet
• B. Genetics
• C. Socio-economic status
• D. Physical activity

Answer: (C)

The factor that shapes how long people live across different populations is socio-economic status because it determines access to the resources and conditions that influence health over the life course. Higher SES generally means safer neighborhoods, stable housing, less chronic stress, better nutrition, and the ability to afford preventive care, medications, and timely treatment. It also affects education, employment opportunities, and the environment in which a person lives, all of which contribute to lower exposure to health risks and better management of chronic conditions. When SES is lower, people often face barriers like crowded housing, food insecurity, limited access to healthcare, and higher exposure to pollutants and unsafe conditions, which accumulate over time and shorten life expectancy. While diet, genetics, and physical activity matter for health, they are often shaped by SES and do not alone account for the large differences seen between populations.