Which of the following is correct for the circulatory system of cockroach?

Options

A. It is present on the dorsal side and it has thirteen units of heart in abdominal region
B. It is present on the ventral side and it has ten abdominal and three thoracic units of heart
C. It is present on the ventral side and it has thirteen units of heart in abdominal region
D. It is present on the dorsal side and it has ten abdominal and three thoracic units of heart

Answer

To solve the question regarding the circulatory system of cockroaches, we need to analyze the statements provided and determine which one is correct.

### Step-by-Step Solution:

1. **Understanding the Circulatory System of Cockroaches**:
- Cockroaches have an open circulatory system, which means that their blood (hemolymph) is not confined to vessels but flows freely in the body cavity.

2. **Location of the Heart**:
- The heart of the cockroach is located on the **dorsal side** of the body, not the ventral side. This is an important distinction.

3. **Number of Heart Units**:
- The cockroach has a total of **13 heart chambers**. These are divided into:
- **3 thoracic units** (located in the thorax)
- **10 abdominal units** (located in the abdomen)

4. **Evaluating the Statements**:
- **Statement 1**: "It is present on the dorsal side and it has 13 units of heart in the abdominal region."
- This statement is incorrect because while it correctly states that the heart is on the dorsal side, it incorrectly states that all 13 units are in the abdominal region. Only 10 are in the abdomen, and 3 are in the thorax.
- **Statement 2**: "It is present on the ventral side."
- This statement is incorrect as the heart is located on the dorsal side.
- **Statement 3**: "It is present on the ventral side and it has 13 units of the heart in the abdominal region."
- This statement is also incorrect for the same reasons as above.
- **Statement 4**: "It is present on the dorsal side and it has 10 abdominal and 3 thoracic units of heart."
- This statement is correct as it accurately describes the location and the number of heart units.

5. **Conclusion**:
- The correct answer is **Option 4**: "It is present on the dorsal side and it has 10 abdominal and 3 thoracic units of heart."