**Speedometer**

The correct answer is option 'C', the speedometer.

**Explanation:**

A speedometer is a device that measures and displays the speed of a vehicle. It is an essential instrument found on the dashboard of a vehicle. The speedometer provides real-time information about the speed at which the vehicle is traveling.

Here is a detailed explanation of each option and why the correct answer is the speedometer:

**a) Ammeter:**
An ammeter is a device used to measure electric current. It is not used to measure the speed of a vehicle. Therefore, option 'a' is incorrect.

**b) Odometer:**
An odometer is a device used to measure the distance traveled by a vehicle. It keeps track of the total distance covered by the vehicle since it was first used. While an odometer is related to measuring distance, it does not directly provide information about the speed at which the vehicle is traveling. Therefore, option 'b' is incorrect.

**c) Speedometer:**
A speedometer is a device specifically designed to measure and display the speed of a vehicle. It consists of a dial or digital display with markings indicating different speed values. The speedometer is connected to the transmission or wheel of the vehicle, and it measures the rotational speed of the wheels. By using the rotational speed, the speedometer calculates and displays the speed at which the vehicle is traveling. Therefore, option 'c' is the correct answer.

**d) Voltmeter:**
A voltmeter is a device used to measure electric potential difference, also known as voltage. It is used to measure the electrical voltage in a circuit. It is not designed to measure the speed of a vehicle. Therefore, option 'd' is incorrect.

In conclusion, the speed of a vehicle is recorded by the speedometer, which is specifically designed to measure and display the speed at which the vehicle is traveling.

Speedometer is a device which help to calculate the speed of the vehicle