Final answer:
The coefficient of performance (COP) for an electric resistance heater is 1, since it converts 1 watt of electrical energy directly into 1 watt of usable heat, meaning the efficiency is 100%.
Step-by-step explanation:
The coefficient of performance (COP) for an electric resistance heater is a measure of its energy efficiency. For an electric resistance heater, 1 watt of electrical energy is converted directly into 1 watt of usable heat. This means that the heat output is equal to the electrical energy input. Since COP is a ratio of useful heating or cooling provided to work required, the COP of electric resistance heat would be COP = heat output / energy input = 1W / 1W = 1. Therefore, the correct answer is b) 1. This implies that electric resistance heaters are 100% efficient at converting electric energy into heat, which is true when considering only the conversion process and ignoring other factors like heat losses to the surroundings.