Introduction:
Disease is a condition that affects the normal functioning of the body. In this question, we are asked to identify the correct definition of a disease.
Definition of Disease:
A disease can be defined as a condition in which the body does not function properly. It can affect various parts of the body, including organs, tissues, and cells, leading to a disruption in normal bodily processes.
Explanation:
To answer this question, we need to analyze the given options and determine which one accurately describes a disease.
Option A: When our bones do not function properly
- This option is incorrect because a disease is not limited to bone-related issues only. It can affect any part of the body, including bones, but it is not exclusive to bone-related conditions.
Option B: When our body does not function properly
- This option is correct. A disease refers to any condition that affects the normal functioning of the body. It can manifest in various ways, such as through symptoms, abnormalities, or imbalances in bodily processes.
Option C: Both A and B
- This option is incorrect because while some diseases may affect bones, not all diseases are bone-related. Therefore, the correct answer cannot be both A and B.
Option D: None of the above
- This option is incorrect as option B accurately defines a disease.
Conclusion:
In conclusion, the correct answer is option B: "When our body does not function properly." A disease is a condition that affects the normal functioning of the body, encompassing various organs, tissues, and cells.

Understanding Disease
When we talk about disease, we refer to a condition that affects the overall function of the body. While bones are indeed vital for our physical structure and health, disease encompasses a broader spectrum.

What is a Disease?
- A disease is defined as a condition that disrupts normal bodily functions.
- It can affect any system within the body, including the respiratory, digestive, and nervous systems, not just the bones.

Why Option B is Correct?
- **Broader Impact**: Option B, which states "When our body does not function properly," accurately captures the essence of disease, as it includes all aspects of bodily functions.
- **Various Causes**: Diseases can result from infections, genetic issues, environmental factors, and lifestyle choices, impacting how the entire body operates.

Examples of Diseases
- **Infectious Diseases**: Such as the flu or COVID-19, which affect the immune system and overall health.
- **Chronic Diseases**: Like diabetes or heart disease, which alter how organs function over time.

Conclusion
While bone health is important, diseases can affect many other aspects of our bodily functions. Hence, the correct answer is option 'B', as it encompasses the full scope of what a disease represents in relation to the human body. Understanding this helps us recognize the significance of health across all bodily systems.