The correct answer is B. Regulators would be most likely to review the bank's accountability standards for its senior managers to ensure the managers behave in a manner that promotes proper conduct. This is because regulators aim to ensure that the bank's risk culture framework and policies regarding conduct and culture are aligned with best practices. Reviewing accountability standards for senior management is a direct way to influence and shape the bank's conduct and culture from the top down.

Option A is incorrect because conduct and culture are not directly addressed by regulatory risk capital requirements. While poor conduct and culture can increase operational losses, the Basel operational risk capital requirements are primarily responsive to net income and reported operational losses, not the expected ones.

Option C is incorrect as traditional, quantitative approaches are not easily applicable to the qualitative aspects of conduct and culture within an organization.

Option D is also incorrect because increasing the proportion of incentive compensation could potentially lead to poorer conduct and a less conservative risk culture. This could, in turn, increase the bank's risk exposure, which is contrary to the regulators' intentions to improve risk management and conduct within the bank.