The commercial unit of electrical energy is measured in kilowatt-hours (kWh). This unit is used to quantify the amount of energy consumed or produced over a period of time.

Option 1 states that 1 kilowatt-hour (kWh) is equal to 3.6 × 10^6 joules (J). This means that if a device consumes or produces 1 kilowatt-hour of energy, it is equivalent to 3.6 × 10^6 joules of energy.

Option 2 states that 1 kilowatt-hour (kWh) is equal to 3.6 × 10^3 joules (J). However, this is incorrect. The correct conversion factor is 3.6 × 10^6 joules, as mentioned in option 1.

Option 3 states that 1 kilowatt-hour (kWh) is equal to 10^3 joules (J). This is incorrect as well. The correct conversion factor is 3.6 × 10^6 joules, as mentioned in option 1.

Option 4 states that 1 kilowatt-hour (kWh) is equal to 1 joule (J). This is also incorrect