Comb-jellies are________animals.

Options

A. Sessile
B. Free-swimming
C. Terrestrial
D. Fresh water

Explanation

To answer the question "Comb-jellies are________animals," we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Group**: Comb jellies belong to the phylum Ctenophora. This is the first step in understanding their classification.

2. **Understand Their Habitat**: Members of the phylum Ctenophora are primarily marine animals. This means they live in saltwater environments.

3. **Determine Their Movement**: Comb jellies are not sessile (attached to a surface), nor are they terrestrial (land-dwelling) or freshwater (living in freshwater bodies). They are known for their ability to move freely in the water.

4. **Define Their Nature**: Since comb jellies float and swim in the water, they can be classified as "free swimming" animals. This is a key characteristic of their behavior.

5. **Eliminate Incorrect Options**:
- Sessile: Incorrect, as they are not attached to any surface.
- Free swimming: Correct, as they move freely in the water.
- Terrestrial: Incorrect, as they do not live on land.
- Freshwater: Incorrect, as they are marine organisms.

6. **Final Answer**: Based on the analysis, the correct answer to the question is that comb jellies are "free swimming" animals.

### Final Answer:
Comb-jellies are **free swimming** animals.

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