In a control system the output of the controller is given to

The correct answer is: A. Final control element

A final control element is a device that is used to control the process variable in a control system. It is the last element in the control loop and is responsible for implementing the control action. The output of the controller is given to the final control element, which then adjusts the process variable to the desired value.

The other options are incorrect because:

• An amplifier is a device that increases the power of a signal. It is used in control systems to increase the output signal of the controller so that it can drive the final control element.
• A comparator is a device that compares two signals. It is used in control systems to determine whether the process variable is within the desired range.
• A sensor is a device that measures a physical quantity and converts it into an electrical signal. It is used in control systems to measure the process variable.