How does a proportional controller affect the system response?

A proportional controller adjusts the output based on the current error between the desired setpoint and the actual process variable. This means that the controller calculates the difference, known as the error, and then modifies the control output in direct proportion to that error value. The greater the error, the larger the output adjustment, which helps the system respond more effectively to changes and brings the process variable closer to the desired setpoint.

This approach allows the system to maintain a balance: as the error decreases, the output adjustment also reduces, smoothing out oscillations to some extent. However, it's important to note that while a proportional controller can improve system response, it does not eliminate the steady-state error completely unless combined with integral or derivative actions.

The other options do not accurately reflect how a proportional controller operates. For instance, ignoring the error entirely would not provide any control response, and adjusting the output based on the average error does not take into account the current state of the system. Introducing oscillations in the output is more characteristic of an overly aggressive control action or poor tuning rather than a standard feature of proportional control.