Waste product of mammal is -

Options

A. Ammonia
B. Urea
C. Uric acid
D. Guanine

Answer

### Step-by-Step Solution:

1. **Identify the Question**: The question asks for the waste product of mammals.

2. **Understand the Options**: The possible waste products mentioned are ammonia, urea, uric acid, and guanine.

3. **Analyze Each Waste Product**:
- **Ammonia**: Highly toxic and primarily excreted by aquatic animals, including many fish.
- **Urea**: Less toxic than ammonia and is the primary waste product of mammals. It is produced in the liver and excreted by the kidneys.
- **Uric Acid**: Less soluble and more energy-intensive to produce, uric acid is primarily excreted by birds and reptiles.
- **Guanine**: This is not a common waste product; it is more associated with certain invertebrates.

4. **Conclude the Best Answer**: Since mammals primarily excrete urea, the answer to the question is urea.

5. **Final Answer**: The waste product of mammals is urea.