To ensure the accuracy of a pneumatic controller throughout its range, you must precisely adjust all of the following EXCEPT:

In the context of maintaining the accuracy of a pneumatic controller, precise adjustment is crucial for the performance of the system. The zero and span adjustments, along with the input, play significant roles in calibrating the controller to ensure it responds correctly to variations in process conditions.

Zero refers to the calibration point where the controller indicates zero output when no input is present. Adjusting the zero ensures that the system can accurately reflect the starting point of measurement.

Span adjustment is essential for defining the range of the output signal concerning the input range. By accurately setting the span, you ensure that the controller can represent the full scale of input changes effectively.

The input adjustment pertains to the signals received by the controller from the process variable. Calibration of the input ensures that any variations in the input correctly correspond to changes in the output.

On the other hand, while supply pressure is important for the operation of pneumatic controllers, it typically does not require precise adjustments for maintaining the accuracy of the output across the entire range. As long as the supply pressure is within an acceptable operating range, the controller can function correctly. Thus, the correct choice indicates that supply pressure does not require the same level of precise adjustment as the zero, span, and input settings.