In cockroach, air from atmosphere enters by

Options

A. Trachea
B. Tracheoles
C. Spiracles
D. Chitin

Explanation

### Step-by-Step Solution:

1. **Identify the Organism**: The question refers to the cockroach, which is an insect belonging to the phylum Arthropoda.

2. **Understand the Respiratory System**: Cockroaches have a unique respiratory system that consists of a network of tubes called tracheae.

3. **Locate the Entry Points for Air**: Air enters the cockroach's body through small openings on the sides of its body. These openings are known as spiracles.

4. **Count the Spiracles**: Cockroaches have a total of 10 pairs of spiracles, which are strategically located on the lateral sides of their body.

5. **Function of Spiracles**: The spiracles allow atmospheric air to enter the tracheal system, which then distributes oxygen to various parts of the cockroach's body through smaller branching tubes called tracheal tubes.

6. **Clarify Other Options**:
- The term "trachea" refers to the larger tubes that carry air but does not directly refer to the entry points.
- "Chitin" is the material that makes up the exoskeleton of the cockroach and is not involved in air entry.

7. **Conclusion**: Therefore, the correct answer to the question is that air from the atmosphere enters the cockroach through the **spiracles**.

### Final Answer:
In cockroach, air from the atmosphere enters by **spiracles**.