Final answer:
Clinical correspondence relates to patients, clinical matters, and research, often involving communication between healthcare professionals such as clinical psychologists.
Step-by-step explanation:
The type of correspondence that concerns patients, clinical matters, and research is D. Clinical. This type of correspondence includes communication related to patient care, medical reports, treatment plans, and the sharing of research findings within the medical and healthcare community. A professional such as a clinical psychologist may engage in this kind of correspondence, especially when discussing clinical trials or treatments and communicating with other healthcare professionals or institutions.