the respiratory structure in tongue worms is

Options

A. lungs
B. blood-gills
C. tube-feet
D. gills

Explanation

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks about the respiratory structure in tongue worms. We need to identify which of the provided options is correct.

2. **Analyzing the Options**:
- **Option 1: Lungs**: Lungs are primarily found in terrestrial organisms for breathing. Since tongue worms are not terrestrial, this option is incorrect.
- **Option 2: Blood Gills**: Blood gills are not a recognized respiratory structure in tongue worms. Therefore, this option is also incorrect.
- **Option 3: Tube Feet**: Tube feet are characteristic of echinoderms (like starfish), not tongue worms. Thus, this option is incorrect as well.
- **Option 4: Gills**: Gills are respiratory structures found in many aquatic organisms, including hemichordates, which are the group that includes tongue worms. This option is correct.

3. **Conclusion**: Based on the analysis, the correct answer is that the respiratory structure in tongue worms is **gills**.

**Final Answer**: Gills

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