Which of the following best defines an infectious disease?

• A. A disease caused by the invasion and multiplication of pathogenic microorganisms in the body.
• B. A disease resulting from genetic mutations inherited from parents.
• C. A disease that arises due to hormonal imbalances in the body.
• D. A disease caused by physical injury to tissues or organs.

Answer: (A)

Verified step by step guidance

1. Step 1: Understand the term 'infectious disease' by breaking down its components: 'infectious' relates to infection, which involves microorganisms such as bacteria, viruses, fungi, or parasites.
2. Step 2: Recognize that an infectious disease occurs when these pathogenic microorganisms invade the body and multiply, disrupting normal bodily functions.
3. Step 3: Compare this definition with other types of diseases mentioned, such as genetic diseases (caused by inherited mutations), hormonal diseases (caused by imbalances in hormones), and diseases caused by physical injury (trauma to tissues or organs).
4. Step 4: Identify that only the option describing a disease caused by the invasion and multiplication of pathogenic microorganisms matches the definition of an infectious disease.
5. Step 5: Conclude that the best definition of an infectious disease is 'a disease caused by the invasion and multiplication of pathogenic microorganisms in the body.'