Blood has been found to be isotonic with

Options

A. Normal saline solution
B. Saturated `NaCl` solution
C. Saturated `KCl` solution
D. Saturated solution of a 1:1 mixture of `NaCl` and `KCl`

Explanation

To determine what blood is isotonic with, we need to understand the concept of isotonic solutions. An isotonic solution is one that has the same osmotic pressure as another solution, which in this case is blood.

### Step-by-Step Solution:

1. **Understanding Isotonic Solutions**:
- Isotonic solutions have equal concentrations of solutes, which means they exert the same osmotic pressure. This is important for maintaining cell integrity and function.

2. **Identifying Blood's Isotonic Solution**:
- Blood is isotonic with a solution that has a similar concentration of solutes. In biological terms, this is typically a saline solution.

3. **Saline Solution Composition**:
- A saline solution is primarily composed of sodium chloride (NaCl). The concentration of this saline solution that is isotonic with blood is crucial.

4. **Determining the Concentration**:
- The normal saline solution that is isotonic with blood is approximately 0.16 M (molar). This means that a 0.16 M NaCl solution will have the same osmotic pressure as blood.

5. **Conclusion**:
- Therefore, blood has been found to be isotonic with a normal saline solution, specifically a 0.16 M NaCl solution.

### Final Answer:
Blood has been found to be isotonic with a normal saline solution (0.16 M NaCl).