Male and female cockroaches can be distinguished externally by

Options

A. (a) Anal styles in male
B. (b) Anal cerci in female
C. (c) Anal style and antennae in female
D. (d) Both a) and b)

Answer

To distinguish between male and female cockroaches externally, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Features**: Start by examining the external features of male and female cockroaches. Look for structures that are unique to one sex.

2. **Analyze the Options**:
- **Option A: Anal Styles**: These are present only in male cockroaches. They are used during mating.
- **Option B: Annul Circuits**: These are present in both male and female cockroaches. They assist in mating but are not exclusive to one sex.
- **Option C: Antennae**: Both male and female cockroaches have antennae, although their sizes differ (males have thinner antennae while females have thicker ones).
- **Option D: Both A and B**: This option cannot be correct since option B is not exclusive to either sex.

3. **Determine the Correct Answer**: Since anal styles are the only feature that is exclusively found in male cockroaches, the correct answer is **Option A: Anal Styles**.

### Final Answer:
Male and female cockroaches can be distinguished externally by **anal styles**, which are present only in males.

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