The correct option is Cross-sectional area.
Explanation
The electrical resistance of a uniform metallic conductor depends on its geometric dimensions and the intrinsic properties of the material. This relationship is defined by the fundamental laws of resistance.
Detailed Analysis
The resistance ($R$) of a conductor is given by the formula:
$R = \rho \frac{L}{A}$
Where:
- $\rho$ (rho): Resistivity (specific resistance) of the material.
- $L$: Length of the conductor.
- $A$: Cross-sectional area of the conductor.
From this equation, the dependencies are as follows:
- Directly Proportional to Length ($R \propto L$): As the length of the conductor increases, the resistance increases because electrons encounter more collisions over a longer path.
- Inversely Proportional to Cross-sectional Area ($R \propto \frac{1}{A}$): As the cross-sectional area increases (i.e., the wire becomes thicker), the resistance decreases because there is a wider path for the flow of electrons.
Key Takeaway: For a specific material, resistance is directly proportional to the length of the wire and inversely proportional to its thickness (cross-sectional area).