Diseases are broadly grouped into infectious and non-infectious deseases. In the list given below, identify the infectious diseases.
(i) Cancer , (ii) Influenza
(iii) Allergy, (iv) Small pox

Options

A. (i) and (ii)
B. (ii) and (iii)
C. (iii) and (iv)
D. (ii) and (iv)

Explanation

To identify the infectious diseases from the given list, we can follow these steps:

### Step 1: Understand the Classification of Diseases
Diseases can be classified into two main categories: infectious and non-infectious diseases. Infectious diseases are caused by pathogens (like bacteria, viruses, fungi, or parasites) and can be transmitted from one individual to another. Non-infectious diseases are not caused by pathogens and cannot be transmitted.

### Step 2: Analyze Each Disease in the List
We will go through each disease in the list to determine if it is infectious or non-infectious.

1. **Cancer**:
- Cancer is caused by mutations in DNA and is not caused by infectious agents. Therefore, it is classified as a non-infectious disease.

2. **Influenza**:
- Influenza is caused by the Influenza virus. Since it is caused by a virus and can be transmitted from one person to another, it is classified as an infectious disease.

3. **Allergy**:
- Allergies are caused by allergens (substances that trigger an allergic reaction) and are not caused by infectious agents. Thus, allergies are considered non-infectious diseases.

4. **Smallpox**:
- Smallpox is caused by the variola virus. It is an infectious disease because it can be transmitted between individuals.

### Step 3: Identify the Infectious Diseases
From the analysis:
- Infectious diseases identified: Influenza and Smallpox.
- Non-infectious diseases identified: Cancer and Allergy.

### Conclusion
The infectious diseases from the list provided are Influenza and Smallpox. Therefore, the correct answer is option D: second and fourth.

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