The resistivity does not change if :

Options

A. the material is changed
B. the temperature is changed
C. the shape of the resistor is changed
D. both material and temperature are changed

Explanation

To solve the question "The resistivity does not change if:", we need to understand the properties of resistivity.

### Step-by-Step Solution:

1. **Understand Resistivity**:
- Resistivity (ρ) is an intrinsic property of a material, meaning it is a characteristic of the material itself and does not depend on the shape or size of the object made from that material.

2. **Identify Key Properties**:
- Resistivity is constant for a given material at a specific temperature.
- It increases with temperature for most conductors.
- It does not depend on the shape or size of the conductor.

3. **Analyze the Options**:
- **Option A**: If the material is changed, the resistivity will change. (False)
- **Option B**: If the temperature is changed, the resistivity will change for most conductors. (False)
- **Option C**: If the shape of the resistor is changed, the resistivity does not change. (True)
- **Option D**: If both material and temperature are changed, the resistivity will change. (False)

4. **Conclusion**:
- The only correct option is **Option C**: "The resistivity does not change if the shape of the resistor is changed."