The 45-year-old son of a client calls the PMHNP to ask her to write a letter declaring his mother incompetent, and therefore unable to make medical decisions for herself. What is the most appropriate response?

"Your mother is perfectly competent."

"Competence is a legal concept, not a medical one. I have no authority to do such a thing."

"I have been worrying about your mother for a while; I'm glad you are taking steps to get her help."

"I can't help you, but I can direct you to someone who can."