Explanation:

- Spread of Communicable Diseases: Overcrowding and global travel contribute to the spread of diseases like influenza and COVID-19, increasing health burdens worldwide.

- Respiratory System Issues: Pollution and smoking exacerbate conditions like asthma and chronic obstructive pulmonary disease (COPD), leading to significant health challenges.

- Lifestyle of People: Sedentary habits, poor diet, and stress contribute to chronic illnesses such as obesity, diabetes, and heart disease, elevating global health burdens.

- All of the Above: The combination of these factors leads to an increasing burden of disease globally, affecting millions.

Correct Answer: Option 4 - All of the above