Cockroach, house fly and mosquitoes are insect because they have :-

Options

A. Chitinous exoskeleton and body divided into head and cephalothorax
B. Six legs , compound eyes and body divided into head, thorax and abdomen
C. Segmented body with jointed feet and chitinous exoskeleton
D. Three pairs of legs, one pair of antennae and flame cells

Answer

To determine why cockroaches, houseflies, and mosquitoes are classified as insects, we need to analyze the characteristics that define this group of animals. Here’s a step-by-step breakdown of the reasoning:

### Step-by-Step Solution:

1. **Understanding Insect Classification**: Insects belong to the class Insecta and have specific characteristics that differentiate them from other arthropods.

2. **Analyzing the Options**:
- **Option 1**: "Kitinous exoskeleton and body divided into the head and cephalothorax."
- This option is incorrect because insects have a body divided into three parts: head, thorax, and abdomen, not cephalothorax (which is characteristic of arachnids).

- **Option 2**: "6 legs, compound eyes, and body divided into the head, thorax, and abdomen."
- This option is correct. Insects have six legs (three pairs), compound eyes for better vision, and their body is indeed divided into three distinct regions: head, thorax, and abdomen.

- **Option 3**: "Segmented body with jointed feet and cutaneous exoskeleton."
- This option is misleading. While insects do have a segmented body and jointed appendages, the term "cutaneous exoskeleton" is not specific to insects. Moreover, insects typically have a chitinous exoskeleton.

- **Option 4**: "3 pairs of legs, 1 pair of antennae, and flame cells."
- This option is incorrect because while insects do have three pairs of legs and one pair of antennae, flame cells are not a feature of insects; they are found in flatworms.

3. **Conclusion**: The defining characteristics of insects, such as having six legs, compound eyes, and a body divided into three parts (head, thorax, abdomen), confirm that cockroaches, houseflies, and mosquitoes are indeed classified as insects.

### Final Answer:
Cockroach, housefly, and mosquitoes are insects because they have **6 legs, compound eyes, and their body is divided into the head, thorax, and abdomen**.

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