Answer: where management expects the firm to operate.
Step-by-step explanation:
Company planning is the duty of management and and they plan, they try to use a certain range of activity so that they can better predict how the company will go. That range is therefore the range that the management of the company expects the firm to operate.
When production actually starts, management will try to either keep to that range or exceed it so as to meet or exceed expectations. And even if they don't meet this expectation, they use this relevant range to compare to the actual range for performance evaluation.