Croaking of frog is 

Options

A. Sign of danger
B. Call of hunger
C. Sex call for male
D. Sex call for female

Answer

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks about the significance of the croaking sound made by frogs.

2. **Identifying the Source of Croaking**: It is important to note that croaking is primarily produced by male frogs. They possess vocal cords that allow them to produce these sounds.

3. **Timing of Croaking**: Male frogs tend to croak more loudly during their mating season, particularly at night. This is a critical time for them to attract females.

4. **Purpose of Croaking**: The primary purpose of the croaking sound is to attract female frogs for mating. Male frogs croak to signal their presence and to entice females.

5. **Environmental Triggers**: Male frogs may also croak in response to environmental sounds, such as running water or other loud noises, which can help amplify their calls.

6. **Conclusion**: Based on the above points, the croaking of frogs is best described as a "sex call for females." It is not a sign of danger or a call for hunger.

### Final Answer:
The croaking of frogs is a sex call for females.

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