**Core Concept**
The Glasgow Coma Scale (GCS) is a neurological scale used to assess the level of consciousness in patients. It evaluates three aspects of consciousness: eye opening, verbal response, and motor response. The scale ranges from 3 to 15, with 3 being the lowest score.

**Why the Correct Answer is Right**
The minimum possible score in the GCS is achieved when a patient exhibits no response to verbal commands, does not open their eyes, and has no motor response. This corresponds to a score of 3, as the patient is unresponsive and cannot be roused. The GCS is a widely used tool in clinical settings to assess the severity of head injuries and other conditions affecting consciousness.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not correspond to a valid score on the GCS.
**Option B:** This option is incorrect because the maximum possible score is 15, not a negative number.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that the GCS is a sensitive tool for assessing the level of consciousness in patients. A score of 3 or less is often associated with poor outcomes, and prompt medical attention is necessary to improve survival and quality of life.

**Correct Answer: C. 3**