Physical activity is thought to reduce the risk of colon cancer by:

• A. reducing the absorption of dietary fiber
• B. increasing the rate of DNA mutations in colon cells
• C. inhibiting apoptosis in abnormal colon cells
• D. decreasing inflammation and improving immune function

Answer: (D)

Verified step by step guidance

1. Understand the role of physical activity in overall health: Physical activity is known to have systemic benefits, including reducing inflammation and enhancing immune function, which are key factors in cancer prevention.
2. Clarify the connection between inflammation and colon cancer: Chronic inflammation can lead to an environment that promotes cancer development. Physical activity helps reduce inflammation, thereby lowering the risk of colon cancer.
3. Explain the role of the immune system in cancer prevention: A strong immune system can identify and eliminate abnormal cells, including those that may become cancerous. Physical activity improves immune surveillance and function.
4. Eliminate incorrect options: Reducing the absorption of dietary fiber, increasing DNA mutations, or inhibiting apoptosis are not mechanisms by which physical activity reduces colon cancer risk. In fact, dietary fiber is beneficial, DNA mutations are harmful, and apoptosis is a protective process.
5. Conclude with the correct mechanism: Physical activity reduces the risk of colon cancer primarily by decreasing inflammation and improving immune function, creating a healthier cellular environment in the colon.