Final answer:
Situation C, where an audit partner has a brother with a significant investment in an audit client and the partner is part of the audit, violates Rule 101 of the AICPA Code of Professional Conduct on independence.
Step-by-step explanation:
Among the situations presented that would violate Rule 101 of the AICPA Code of Professional Conduct, which relates to independence, the situation that specifically constitutes a violation is:
C. An audit partner has a brother who owns a 20% interest in an audit client, which is material to the brother's net worth. The partner participates in the audit engagement and is aware of his brother's investment.
This scenario breaches independence requirements because the audit partner is considered a covered member due to their direct participation in the audit. The material financial interest that the partner's brother holds in the client creates a self-interest threat that cannot be mitigated sufficiently, thus impairing the auditor's independence. According to the AICPA Code of Professional Conduct, family relationships involving material financial interests in the audit client can create impairments to independence when the auditor is directly associated with the engagement.
Conversely, scenarios A and B do not constitute violations under Rule 101: