Rotifers are

Options

A. Unicellular animals
B. Multicellular animals
C. Smallest metazoans
D. Both B and C .

Answer

**Step-by-Step Solution:**

1. **Understanding Rotifers**: Begin by identifying what rotifers are. They are small aquatic animals commonly found in freshwater environments.

2. **Cellularity**: Determine whether rotifers are unicellular or multicellular. Rotifers are multicellular organisms, meaning they are composed of more than one cell.

3. **Metazoans**: Recognize that rotifers belong to the category of metazoans, which are multicellular animals. They are considered the smallest metazoans due to their size.

4. **Digestive System**: Note that rotifers have a complete digestive tract, which means they have a system that runs from mouth to anus. This feature is significant in classifying them as multicellular organisms with specialized organ systems.

5. **Conclusion**: Based on the above points, we can conclude that rotifers are multicellular animals and also the smallest metazoans.

6. **Answer Selection**: Given the options:
- A) Unicellular animal
- B) Multicellular animal
- C) Smallest metazoans
- D) Both B and C

The correct answer is option D, as both B (multicellular animal) and C (smallest metazoans) are true.

**Final Answer**: Rotifers are multicellular animals and the smallest metazoans; therefore, the correct answer is option D (both B and C).

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