Which external trait determines sex correctly

Options

A. Female Cockroach- Anal cerci
B. Male Shark- claspers on plevic fins
C. Female Ascaris- Curved posterior end
D. Male Frog-Copulatory pad on first digit of hind limb

Answer

To determine which external trait correctly identifies sex among the given options, we will analyze each option step by step.

### Step-by-Step Solution:

1. **Identify the Options**:
- Female cockroach with anal cerci
- Male shark with claspers on pelvic fin
- Female Ascaris with curved posterior end
- Male frog with copulatory pad on the first digit of hind limb

2. **Analyze Each Option**:
- **Option 1: Female Cockroach with Anal Cerci**:
- Anal cerci are paired appendages found at the end of the abdomen in cockroaches. They are present in both male and female cockroaches, making this option incorrect as it does not distinctly identify sex.

- **Option 2: Male Shark with Claspers on Pelvic Fin**:
- Male sharks possess claspers, which are extensions of the pelvic fins used during mating to transfer sperm to the female. This trait is specific to males, making this option correct.

- **Option 3: Female Ascaris with Curved Posterior End**:
- In Ascaris, it is actually the male that has a curved posterior end, while females have a straight posterior end. Therefore, this option is incorrect.

- **Option 4: Male Frog with Copulatory Pad on First Digit of Hind Limb**:
- The copulatory pad in male frogs is located on the first digit of the forelimb, not the hind limb. Thus, this option is also incorrect.

3. **Conclusion**:
- The external trait that correctly determines sex is the **Male Shark with Claspers on Pelvic Fin**.

### Final Answer:
The correct answer is **Male Shark with Claspers on Pelvic Fin**.

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