There are three animals X, Y and Z . The animal X can stay in water as well as on land and can breathe through its moist skin as well as lungs. The animal Y always lives in water and had gills for breathing. On the other hand, animal Z lives in soil and breathes only through its skin.
Which animal could be a frog

Answer

To determine which animal could be a frog among the three animals X, Y, and Z, we can analyze the characteristics of each animal based on the information provided.

### Step-by-Step Solution:

1. **Analyze Animal X**:
- Animal X can stay in water as well as on land.
- It can breathe through its moist skin and lungs.
- Frogs are known to be amphibians, which can live both in water and on land and breathe through their skin (cutaneous respiration) and lungs.

**Conclusion for X**: Animal X fits the description of a frog.

2. **Analyze Animal Y**:
- Animal Y always lives in water.
- It has gills for breathing.
- Animals that live exclusively in water and have gills are typically fish.

**Conclusion for Y**: Animal Y is likely a fish.

3. **Analyze Animal Z**:
- Animal Z lives in soil.
- It breathes only through its skin.
- Organisms that live in soil and breathe through their skin are often earthworms or similar soil-dwelling organisms.

**Conclusion for Z**: Animal Z is likely an earthworm.

4. **Final Conclusion**:
- Based on the analysis, Animal X, which can live both in water and on land and can breathe through its skin and lungs, is the one that could be a frog.

### Answer:
Animal X could be a frog.