**Core Concept**
Consultation-liaison (C-L) psychiatry is a subspecialty of psychiatry that focuses on the diagnosis and treatment of psychiatric disorders in medically ill patients. It involves the collaboration between psychiatrists and other healthcare professionals to address the complex psychological and psychiatric needs of patients with medical conditions.

**Why the Correct Answer is Right**
C-L psychiatry involves the assessment and management of psychiatric symptoms in patients with medical conditions, such as cancer, HIV, or neurological disorders. This requires a comprehensive understanding of the interplay between medical and psychiatric illnesses, as well as the ability to develop treatment plans that take into account the patient's overall medical condition. C-L psychiatrists work closely with other healthcare professionals, including primary care physicians, surgeons, and specialists, to provide coordinated care.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because C-L psychiatry is not limited to the treatment of patients with only one medical condition. In reality, C-L psychiatrists often encounter patients with multiple complex medical conditions.
**Option B:** This option is incorrect because C-L psychiatry is not a separate medical specialty, but rather a subspecialty of psychiatry. While C-L psychiatrists may work closely with other healthcare professionals, they are still psychiatrists by training and expertise.
**Option C:** This option is incorrect because C-L psychiatry is not solely focused on the treatment of patients with chronic illnesses. While many patients with chronic illnesses may require C-L psychiatric services, the subspecialty is not limited to this population.

**Clinical Pearl / High-Yield Fact**
C-L psychiatry is a high-yield area for medical students and residents, as it requires a comprehensive understanding of the interplay between medical and psychiatric illnesses. By recognizing the complex psychological and psychiatric needs of medically ill patients, healthcare professionals can provide more effective and coordinated care.

**Correct Answer: C. C-L psychiatry involves the diagnosis and treatment of psychiatric disorders in medically ill patients.**