Why would a large size resistor be used instead of a smaller one of the same resistance?

The physical size of a resistor determines its ability to dissipate heat, not its electrical resistance. When current flows through a resistor, electrical energy is converted into heat. If the resistor cannot safely dissipate this heat into the surrounding air, it will overheat and fail. A larger physical size provides a greater surface area, which allows the resistor to radiate heat more effectively into the environment. This is why a 100-ohm, 10-watt resistor is physically much larger than a 100-ohm, 1/4-watt resistor, even though their resistance values are identical. Options mentioning conductance, response time, or impedance are incorrect because physical size does not alter the fundamental resistance or reactive properties of the component, only its thermal capacity.