Who is responsible for ensuring that the project remains viable in terms of Business Case?
Correct: The Executive owns the Business Case and is accountable for viability.
Why this answer
The Executive is the single individual on the Project Board who has ultimate accountability for the project's business justification. They own the Business Case and must ensure it remains viable throughout the project lifecycle, approving any changes that affect its viability. The Project Manager manages the day-to-day work but does not own the Business Case; the Executive alone is responsible for its ongoing viability.
Exam trap
The trap here is that candidates often assume the Project Board as a whole is responsible for the Business Case, but PRINCE2 specifically assigns this accountability to the Executive alone, making the Board's role collective approval rather than individual ownership.
How to eliminate wrong answers
Option A is wrong because the Project Board as a whole is responsible for overall project direction and approval, but the Executive is the specific member who owns the Business Case and is accountable for its viability. Option C is wrong because the Project Manager manages the project on a day-to-day basis and provides information for the Business Case, but does not own it or have authority to decide on its viability. Option D is wrong because the Senior User represents the users' interests and specifies benefits, but does not own the Business Case or have accountability for its viability.