Normal microbiota:

• A. Are the organisms that typically reside on and in your body.
• B. Protect against infection by pathogens.
• C. Enhance infection by pathogens.
• D. Play no role in affecting pathogen growth.
• E. A and B.
• F. C and D.

Answer: (E)

Verified step by step guidance

1. Understand the concept of normal microbiota: These are the microorganisms that naturally live on and inside the human body, such as bacteria, fungi, and viruses, without causing disease under normal circumstances.
2. Consider the role of normal microbiota in protecting against infection: They compete with pathogens for nutrients and space, produce substances harmful to pathogens, and stimulate the immune system.
3. Evaluate the statement 'Enhance infection by pathogens': Normal microbiota typically do not enhance infections; instead, they help prevent them by maintaining a balanced microbial environment.
4. Assess the statement 'Play no role in affecting pathogen growth': This is incorrect because normal microbiota do play a significant role in inhibiting pathogen growth through various mechanisms.
5. Conclude that the correct answers are A and B, as normal microbiota reside on and in the body and protect against infection by pathogens, while C and D are incorrect.