Which Item Is an Indication of Credibility Under the Standards

Which item is an indication of credibility under the Standards of Ethical Conduct?

A) Maintain an appropriate level of professional expertise by continually developing knowledge and skills.
B) Refrain from using confidential information for unethical or illegal advantage.
C) Abstain from engaging in or supporting any activity that might discredit the profession.
D) Disclose delays or deficiencies in information, timeliness, processing, or internal controls in conformance with organization policy and/or applicable law.