Which of the following is NOT a factor that weakens host defenses against infections?

• A. Malnutrition
• B. Regular physical exercise
• C. Immunosuppressive drugs
• D. Chronic stress

Answer: (B)

Verified step by step guidance

1. Step 1: Understand the concept of host defenses, which are the mechanisms by which the body protects itself against infections, including physical barriers, immune responses, and overall health status.
2. Step 2: Identify factors that weaken host defenses. These typically include conditions or behaviors that impair the immune system or reduce the body's ability to fight infections, such as malnutrition, immunosuppressive drugs, and chronic stress.
3. Step 3: Analyze each option given in the problem: Malnutrition reduces essential nutrients needed for immune function; immunosuppressive drugs deliberately reduce immune activity; chronic stress can impair immune responses over time.
4. Step 4: Consider the role of regular physical exercise. Unlike the other factors, regular physical exercise generally strengthens the immune system and improves overall health, thus enhancing host defenses rather than weakening them.
5. Step 5: Conclude that the factor which does NOT weaken host defenses is regular physical exercise, as it supports and boosts the body's ability to resist infections.