Final answer:
The most critical step to improve business ethics is for top management to adopt and support a corporate code of conduct.
Step-by-step explanation:
The most critical step to help improve business ethics is A. Top management must adopt and support a corporate code of conduct. A corporate code of conduct sets the standards and expectations for ethical behavior within an organization. It provides a guideline for employees to follow and ensures that ethical practices are prioritized from the top-down.