Radial symmetry is often exhibited by animals having

Options

A. one opening of alimentary canal
B. aquatic mode of living
C. benthos/sedentary
D. ciliary mode of feeding

Explanation

**Step-by-Step Solution:**

1. **Understanding Radial Symmetry**:
- Radial symmetry refers to a body plan in which the body can be divided into similar halves by multiple planes passing through the central axis. This means that if you were to slice the organism in any direction, you would get two equal halves.

2. **Characteristics of Radial Symmetry**:
- Organisms exhibiting radial symmetry typically have a central point from which their body parts radiate outwards. This type of symmetry is commonly found in simpler, more primitive organisms.

3. **Habitat of Radially Symmetrical Animals**:
- Most animals that exhibit radial symmetry are aquatic. They are often found in marine environments, such as oceans and seas. This is because radial symmetry allows these organisms to interact with their environment in a way that is advantageous for their survival in water.

4. **Evaluating the Options**:
- **Option 1**: "One opening of the elementary canal" - This is not a universal trait of radially symmetrical animals, as some, like echinoderms, have two openings (mouth and anus).
- **Option 2**: "Aquatic mode of living" - This is a common characteristic of radially symmetrical animals, making it a strong candidate for the answer.
- **Option 3**: "Sedentary mode of living" - Not all radially symmetrical animals are sedentary; some can move freely.
- **Option 4**: "Selenium mode of freedom" - This is also not a necessary condition for all radially symmetrical animals.

5. **Conclusion**:
- Based on the evaluation, the best answer is **Option 2: Aquatic mode of living**. This characteristic is commonly associated with animals that exhibit radial symmetry.

**Final Answer**: Radial symmetry is often exhibited by animals having an aquatic mode of living.

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