Which of the following is the SI unit of resistance?

The SI unit of resistance is Ohms, represented by the symbol Ω. Resistance is a measure of how much a material opposes the flow of electric current. When a voltage is applied across a conductor, the amount of current that flows through it is influenced by the resistance present in that conductor.

The relationship between voltage (V), current (I), and resistance (R) is described by Ohm's Law, which states that V = I × R. In this equation, resistance is what dictates how effectively the current can flow for a given voltage.

Other units mentioned do not measure resistance. Amperes is the unit of electric current, which quantifies the flow of electric charge. Volts is the unit for electric potential difference, which represents the work done to move electric charge between two points. Fermis, or femtometers, measure extremely small distances, typically at the subatomic scale, and are not related to electrical properties at all. Thus, Ohms is the only correct choice for the SI unit of resistance.