In the last project, the usability tests substantially exceeded the budget of the test plan.

To prevent usability testing from exceeding budget, active monitoring and control of project resources are critical. The best practice is to regularly check consumed time, costs, and effort against the original estimates, allowing timely adjustments to scope or resources. This is a classic quality control practice aligned with ISO 9001 principles and standard project management methodologies. Option A relates to test preparation, option C concerns reporting and communication, and option D applies after test execution. Only option B deals directly with budget control during the test.