Name the group of viruses causing dengue fever and yellow fever.

Options

A. arboviruses
B. adenoviruses
C. flaviviruses
D. both (1) and (3)

Explanation

To answer the question regarding the group of viruses causing dengue fever and yellow fever, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Diseases**: The question asks about the viruses that cause dengue fever and yellow fever. Both of these diseases are viral infections.

2. **Research the Causative Agents**: We need to determine which viruses are responsible for these two diseases. Dengue fever is caused by the dengue virus, and yellow fever is caused by the yellow fever virus.

3. **Classify the Viruses**: Both the dengue virus and the yellow fever virus belong to a specific group of viruses. Upon research, we find that both of these viruses are classified under the group known as **Flaviviruses**.

4. **Understand the Classification**: Flaviviruses are a subset of a larger group called **Herboviruses**. This means that while Flaviviruses are specifically responsible for dengue and yellow fever, they are also part of the broader category of Herboviruses.

5. **Select the Correct Answer**: The question provides multiple-choice options:
- A. Herbiviruses
- B. Adenoviruses
- C. Flaviviruses
- D. Both 1st and 3rd (Herbiviruses and Flaviviruses)

Since both dengue fever and yellow fever are caused by Flaviviruses, which are also classified under Herboviruses, the correct answer is option D: Both 1st and 3rd.

### Final Answer:
The group of viruses causing dengue fever and yellow fever is **Flaviviruses**, which are also classified under **Herboviruses**. Thus, the correct option is **D** (Both 1st and 3rd).

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