Exam PRINCE2-Practitioner topic 21 question 4 discussion

MANAGING A STAGE BOUNDARY -
At the end of stage 3, the pilot courses have been planned and this work revealed that sales of the health and safety training course were expected to be higher than originally expected. Therefore, the project manager revised the sales forecast for the course. This revised forecast needs to be both reviewed and approved.
Who should review this forecast after it has been updated as part of the 'update the business case' activity?