Which of the following is different from the others?

Options

A. Joule
B. Kilowatt hour
C. Erg
D. Watt

Answer

To solve the question "Which of the following is different from the others?" we need to analyze the options provided:

1. **Joule**
2. **Kilowatt**
3. **Erg**
4. **Watt**

### Step-by-Step Solution:

**Step 1: Identify the nature of each option.**
- **Joule**: This is a unit of energy in the International System of Units (SI).
- **Kilowatt**: This is a unit of power, but it can also refer to energy when discussing kilowatt-hours (kWh), which is a measure of energy.
- **Erg**: This is a unit of energy in the Centimeter-Gram-Second (CGS) system.
- **Watt**: This is a unit of power in the SI system.

**Step 2: Classify the units.**
- **Energy Units**: Joule, Kilowatt (when considering kilowatt-hours), Erg.
- **Power Units**: Watt.

**Step 3: Compare the units.**
- Joule, Kilowatt (as energy), and Erg are all units of energy.
- Watt is a unit of power, which is the rate of energy transfer.

**Step 4: Determine the odd one out.**
Since Joule, Kilowatt (in terms of energy), and Erg are all energy units, while Watt is a unit of power, we can conclude that:

**The correct answer is: Watt (Option 4)**