Final answer:
Regular running, in accordance with the U.S. Department of Health and Human Services (HHS) guidelines, can result in almost four years of increased life expectancy, suggesting that for each person who starts regular running, life expectancy increases by 3 years.
Step-by-step explanation:
The question poses a scenario related to the impact of regular running on life expectancy. Being physically active, specifically through running or other forms of exercise, is generally associated with a variety of health benefits including increased longevity. Based on the information provided, regular aerobic physical activity according to the guidelines of the U.S. Department of Health and Human Services (HHS) can lead to substantial gains in life expectancy, with people exercising at 100 percent of the HHS guidelines gaining almost four years of life. This information suggests that for each additional person who takes up regular running, on average the life expectancy increases. Thus, the answer to the question is that for each additional person who took up regular running for exercise, the average life expectancy increased by 3 years (option 1).
However, it's important to note that many factors contribute to life expectancy, and personal habits like diet, the presence of risky behaviors, and healthcare utilization are all influential. Additionally, the reduction in life expectancy due to obesity is a concern that underscores the benefits of maintaining a healthy level of physical activity.