The presence of salts (NaCl and others) in animal body fluid gives an inference that life originated in the

Options

A. Primitive ocean
B. Rain-water lakes
C. Salt solution
D. All of these

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks about the significance of the presence of salts, specifically sodium chloride (NaCl), in animal body fluids and what it infers about the origin of life.

2. **Historical Context**: It is important to note that the theory of the origin of life in water was proposed by scientists Oparin and Haldane. They suggested that life began in a "primordial soup" in the oceans.

3. **Role of Salts in Life**: Salts like NaCl are essential for various biological functions in animals, including maintaining osmotic balance and nerve function. The presence of these salts in body fluids suggests a connection to the environment where life first evolved.

4. **Marine Environment**: The oceans are known to be rich in salts, including sodium chloride. This supports the idea that life originated in a saline environment, as the composition of body fluids in animals reflects the saline nature of the primordial oceans.

5. **Evaluating Options**:
- **Primitive Ocean**: This option aligns with the theory that life began in the oceans.
- **Rain Water Lakes**: While they contain water, they do not have the same concentration of salts as the ocean.
- **Salt Solution**: This is too broad and does not specifically refer to the natural environment where life originated.
- **All of These**: This option is incorrect as not all environments listed support the idea of life’s origin.

6. **Conclusion**: Based on the evidence and historical theories, the presence of salts in animal body fluids strongly suggests that life originated in the primitive ocean.

**Final Answer**: The presence of salts (NaCl and others) in animal body fluid gives an inference that life originated in the **primitive ocean**.

---