Among the following, identify the derived quantity?

Options

A. speed
B. Temperature
C. length
D. mass

Explanation

To identify the derived quantity among the given options, we need to understand the difference between fundamental and derived quantities.

### Step-by-Step Solution:

1. **Understanding Fundamental and Derived Quantities**:
- Fundamental quantities are basic physical quantities that cannot be expressed in terms of other quantities. Examples include length, mass, and time.
- Derived quantities are those that can be expressed as a combination of fundamental quantities. They are derived from fundamental quantities through mathematical relationships.

2. **Analyzing the Options**:
- **Option 1: Speed**: Speed is defined as the distance traveled per unit time. It can be expressed as:
\[ \text{Speed} = \frac{\text{Distance}}{\text{Time}} = \frac{\text{Length}}{\text{Time}} \]
Since speed is derived from length (a fundamental quantity) and time (another fundamental quantity), speed is a derived quantity.

- **Option 2: Temperature**: Temperature is a measure of thermal energy and is expressed in units such as Celsius, Kelvin, or Fahrenheit. It is considered a fundamental quantity because it does not derive from other quantities.

- **Option 3: Length**: Length is a fundamental quantity measured in meters. It cannot be broken down into other quantities.

- **Option 4: Mass**: Mass is also a fundamental quantity, representing the amount of matter in an object, measured in kilograms. It cannot be derived from other quantities.

3. **Conclusion**:
- Among the options provided, speed is the only derived quantity because it is calculated using the fundamental quantities of length and time.

### Final Answer:
The derived quantity among the options is **Speed** (Option 1).