The function of a measurement system is to perform various tasks related to the measurement process. These tasks can include indicating, recording, and controlling functions. Let's explore each of these functions in detail:

1. Indicating Function:
- The indicating function of a measurement system involves displaying the measured value to the user.
- This function provides real-time information about the quantity being measured.
- It allows the user to monitor and observe the measured value instantly.
- For example, a digital thermometer indicates the temperature on its screen.

2. Recording Function:
- The recording function of a measurement system involves capturing and storing the measured values for future reference.
- It enables the user to keep a record of the measurements over time.
- This function is useful for analysis, comparison, and evaluating trends.
- For instance, a data logger records temperature readings at regular intervals for later analysis.

3. Controlling Function:
- The controlling function of a measurement system involves using the measured values to control a process or system.
- It allows the user to take appropriate actions based on the measured values.
- This function is commonly used in automated systems, where measurements are used to control various parameters.
- For example, a thermostat measures room temperature and controls the heating or cooling system accordingly.

4. Indicating, Recording, and Controlling Function:
- A measurement system can have all three functions - indicating, recording, and controlling.
- This means that the system can display the measured value, record it for future reference, and use it to control a process or system.
- Having all these functions in a measurement system provides comprehensive functionality and versatility.
- It allows the user to not only observe and analyze the measurements but also take appropriate actions based on the measured values.

In conclusion, the correct answer is option 'D' - indicating, recording, and controlling function. A measurement system can perform all three functions, providing real-time information, recording data for future reference, and enabling control over processes or systems.