Which one of the following statements is incorrect?

Options

A. Birds and land snails are uricotelic animals
B. Mammals and frogs are ureotelic animals
C. Aquatic amphibians and aquatic insects are ammonotelic animals
D. Birds and reptiles are ureotelic

Explanation

To determine which statement is incorrect regarding the excretory products of different animals, we can analyze each option step by step.

### Step-by-Step Solution:

1. **Analyze Statement 1**: "Birds and land snails are uricotelic animals."
- **Explanation**: Uricotelic animals excrete uric acid as their primary nitrogenous waste. Birds and land snails indeed excrete uric acid, making this statement **true**.

2. **Analyze Statement 2**: "Mammals and frogs are ureotelic animals."
- **Explanation**: Ureotelic animals excrete urea. Mammals and frogs do excrete urea, so this statement is also **true**.

3. **Analyze Statement 3**: "Aquatic amphibians and aquatic insects are ammonotelic animals."
- **Explanation**: Ammonotelic animals excrete ammonia, which is highly toxic but soluble in water. Aquatic amphibians and aquatic insects do excrete ammonia, making this statement **true**.

4. **Analyze Statement 4**: "Birds and reptiles are ureotelic."
- **Explanation**: This statement is incorrect. Birds and reptiles are primarily uricotelic, as they excrete uric acid, not urea. Therefore, this statement is **false**.

### Conclusion:
The incorrect statement is **Statement 4**: "Birds and reptiles are ureotelic."