C. It prevents compromising the overall quality level of the product. The statement that is correct about the 'keep teams stable' target is that it prevents compromising the overall quality level of the product. The 'keep teams stable' target is a key principle of agile development, which emphasizes the importance of stable, cross-functional teams that can work together effectively over the long term. By keeping teams stable, the organization can build trust, foster collaboration, and improve communication among team members. This, in turn, can help to prevent compromising the overall quality level of the product. The tolerance for cost is set to zero as part of the 'value-driven' target, which emphasizes the need to deliver maximum value with minimum waste. This target is not directly related to the 'keep teams stable' target.

My answer is C as per my personal negative selection. ChatGPT is also opting for C. But to be hones, D seemed also enticing :-|

Keep teams stable Don’t add people to teams In traditional project management, when a project lags behind its schedule, the knee-jerk reaction is often to bolster the team with additional staff. But when doing this, the short-term effect is often to extend the schedule as new team members get up to speed with the project. This is why, in PRINCE2 Agile, cost tolerance (which often translates to human resources) is set at zero.

Check the guide in 6.4.4

See 6.4.4. B is the answer

The 'keep teams stable' target is primarily intended to prevent compromising the overall quality level of the product. This target is important because it helps to maintain the stability of the Agile team throughout the project, which in turn ensures that the team can work effectively and efficiently to produce high-quality outcomes.