Which of the following is a rootless aquatic plant, which portion of the leaf forms a tiny sac for trapping insects?

Options

A. Nepenthes
B. Drosera
C. Utricularia
D. Dionaea

Answer

To solve the question regarding which rootless aquatic plant forms a tiny sac for trapping insects, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Question**: The question asks for a rootless aquatic plant that has a specific adaptation for trapping insects. This indicates that we are looking for a carnivorous plant that lives in water and does not have roots.

2. **Identify the Options**: The options provided are:
- Nepenthes
- Drosera
- Utricularia
- Dionaea

3. **Analyze Each Option**:
- **Nepenthes**: Commonly known as the Pitcher Plant, it is a terrestrial plant that has a pitcher-like structure to trap insects. It is not rootless or aquatic.
- **Drosera**: Known as Sundew, this is also a terrestrial plant that traps insects using glandular hairs on its leaves. It is not rootless or aquatic.
- **Utricularia**: This is known as the Bladderwort. It is a rootless aquatic plant that floats in water and has specialized sacs (bladders) that trap tiny aquatic insects. This matches the description in the question.
- **Dionaea**: Commonly known as the Venus flytrap, this is a terrestrial plant that captures insects using modified leaves. It is not aquatic or rootless.

4. **Select the Correct Answer**: Based on the analysis, the correct answer is **Utricularia** (option 3), as it is a rootless aquatic plant that forms tiny sacs for trapping insects.

### Final Answer:
The rootless aquatic plant that forms a tiny sac for trapping insects is **Utricularia**.