Choice "A" is correct. According to the COSO, demonstrating appropriate behavior by example is the most effective method to transmit a message of ethical behavior throughout an organization. The commitment to ethical behavior begins with the tone at the top, and is best established by management's demonstrated commitment to ethical behavior.Choice "c" is incorrect. Although detection of unethical behavior with improved internal audit resources is important, it is not as effective in transmitting a message of ethical behavior as leadership by example.Choice "d" is incorrect. Realistic goals are an important component of a corporate culture that encourages ethical behavior; unrealistic goals may provide reasons for unethical behavior. But, according to COSO, they are no substitute for a strong commitment by management and an ethical tone at the top.Choice "b" is incorrect. A competent work force supports ethical behavior and provides an environment where ethical behavior will thrive. However, a demonstrated commitment to ethical behavior by management is the most effective method for transmitting a message of ethical behavior throughout the organization.