Which of the following statements is correct about cockroach ?

Options

A. In females, the `6^(th)` sternum is boat- shaped and together with the `7^(th)` and `8^(th)` sterna form a brood or genital pouch
B. In males, the genital pouch is bounded dorsally by `9^(th)` and `10^(th)` sterna and ventrally by the `9^(th)` tergum
C. Females bear a pair of short, threadlike anal styles which are absent in males
D. The `10^(th)` segment has a pair of filamentous structures called anal cerci

Answer

To determine the correct statement about cockroaches, let's analyze each option provided in the question step by step.

### Step 1: Analyze the first statement
1. **Statement**: "In females, the 6th sternum is boat-shaped and together with the 7th and 8th sternum forms a brood or genital pouch."
- **Analysis**: This statement is incorrect because the 6th sternum does not exist in cockroaches. The brood pouch is actually formed by the 7th and 8th sternum, not the 6th.

### Step 2: Analyze the second statement
2. **Statement**: "In males, the genital pouch is bounded dorsally by the 9th and 10th sternum and ventrically by the 9th tergum."
- **Analysis**: This statement is also incorrect. In male cockroaches, the genital pouch is bounded dorsally by the 9th tergum and ventrally by the 9th sternum, not the 9th and 10th sternum.

### Step 3: Analyze the third statement
3. **Statement**: "Females bear a pair of short thread-like annul styles which are absent in males."
- **Analysis**: This statement is incorrect. Annul styles are actually present in male cockroaches and are used as reproductive organs to attract females. Therefore, this statement is false.

### Step 4: Analyze the fourth statement
4. **Statement**: "The 10th segment has a pair of filamentous structures called annulcersi."
- **Analysis**: This statement is correct. Annulcersi are indeed found in both male and female cockroaches in the 10th segment, and they play a role in excretion.

### Conclusion
After analyzing all the statements, the correct statement about cockroaches is:
- **The 10th segment has a pair of filamentous structures called annulcersi.**

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