The following substances are the excretory products in animals. Choose the least toxic from among them

Options

A. Urea
B. Uric acid
C. Ammonia
D. Carbon dioxide

Explanation

To determine the least toxic excretory product among the given substances, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Excretory Products**: The excretory products we need to evaluate are urea, uric acid, ammonia, and carbon dioxide.

2. **Understand Toxicity Levels**:
- Ammonia is known to be the most toxic nitrogenous waste. It requires a large amount of water for its excretion.
- Urea is less toxic than ammonia and requires a moderate amount of water for excretion.
- Uric acid is the least toxic among these nitrogenous wastes and requires minimal water for its removal.

3. **Evaluate Each Substance**:
- **Ammonia**: Most toxic, requires a lot of water.
- **Urea**: Moderately toxic, requires moderate water.
- **Uric Acid**: Least toxic, requires minimal or no water.
- **Carbon Dioxide**: Not an excretory product in the same sense; it diffuses out of the body and is not classified as a nitrogenous waste.

4. **Conclusion**: Based on the toxicity levels and the amount of water required for excretion, uric acid is identified as the least toxic excretory product.

5. **Final Answer**: The least toxic excretory product among the given options is **uric acid**.