As part of the 'controlling a stage' process, the actions taken include authorizing work to be done (2) and taking corrective action (3) as necessary to manage the stage effectively and keep the project on track.
References: PRINCE2 Foundation Training Manual; PRINCE2 2017 Foundation handbook.

In PRINCE2, the role specifically responsible for carrying out risk response actions is referred to as the
'risk actionee'. This role is assigned to an individual who is tasked with implementing the agreed upon actions to address specific risks. The risk owner, on the other hand, is responsible for the overall management of the risk.References: PRINCE2 7 Foundation handbook and official documents.

During the Managing a Stage Boundary process, the Business Case is used to justify the continuing viability of the project. This involves reviewing and, if necessary, updating the Business Case to reflect any changes or new insights that might impact the project's justification. This helps the Project Board make informed decisions about the future progression of the project.References: PRINCE2 7 Foundation handbook and official documents.

One of the key objectives of the Initiating a Project process is to tailor the organization's project management method to suit the specific requirements of the project. This involves adapting processes, controls, roles, responsibilities, and techniques to ensure they are appropriate for the project's context. References:
PRINCE2 Foundation official documentation and study materials.

The Project Board should refer to corporate or programme management for decisions when it is forecast that the project level tolerance will be exceeded. This scenario typically triggers an exception process as the predefined tolerances are fundamental limits within which the Project Board allows the Project Manager to manage the project. References: PRINCE2 Foundation official study guide and materials.