The answer is: C
Explanation
Cleark v. Union States upheld the important principle of professional ethics that "An advocate can disclose information if the client makes any communication in furtherance of an illegal purpose." Therefore, the correct answer is:
C: An advocate can disclose information if the client makes any communication in furtherance of an illegal purpose.
In this case, the court affirmed the principle that an attorney may breach client confidentiality and disclose information if the client is using the attorney's services to further an illegal or fraudulent purpose. This principle balances the duty of confidentiality with the lawyer's obligation to uphold the law and not assist in illegal activities.