The correct option is Watt.
Explanation
Electric power is defined as the rate at which electrical energy is transferred or converted into other forms (such as heat, light, or mechanical energy) in an electric circuit. The International System of Units (SI) assigns specific derived units to measure these physical quantities based on fundamental units.
Option Analysis:
- Watt is Correct: The Watt (W) is the SI unit of electric power. It is defined as the rate of energy consumption of one joule per second ($1 \text{ W} = 1 \text{ J/s}$). In electrical terms, it is the power dissipated when a current of one ampere flows across a potential difference of one volt ($P = V \times I$).
- Joule is Incorrect: The Joule (J) is the SI unit of work or energy. It represents the total amount of energy transferred, not the rate of transfer.
- Volt is Incorrect: The Volt (V) is the SI unit of electric potential difference or electromotive force.
- Coulomb is Incorrect: The Coulomb (C) is the SI unit of electric charge.
Key Takeaway:
The SI unit of electric power is the Watt (W), which measures the rate of energy usage, whereas the Joule (J) measures the total energy.