## **Core Concept**
The McEwan sign, also known as the McEwan sign of alcoholic intoxication, is a clinical indication used to assess the level of alcohol intoxication. It is associated with the level of blood alcohol concentration.

## **Why the Correct Answer is Right**
The McEwan sign is observed when a person is unable to walk a straight line or perform a simple task requiring coordination, indicating significant impairment. Research and clinical observations suggest that a blood alcohol level of **300 mg%** or higher is typically associated with severe intoxication, where such signs become more pronounced. This level of alcohol in the blood significantly impairs motor coordination and cognitive functions.

## **Why Each Wrong Option is Incorrect**
- **Option A:** 100 mg% - This level of blood alcohol concentration is associated with mild to moderate impairment but not typically with the severe signs like McEwan sign.
- **Option B:** 200 mg% - While this level indicates significant intoxication and impairment, it is generally below the threshold where severe signs like McEwan sign are consistently observed.
- **Option D:** 400 mg% - Although very high, the specific association of McEwan sign is more accurately correlated with a level of **300 mg%**.

## **Clinical Pearl / High-Yield Fact**
A key clinical correlation to remember is that blood alcohol levels above **300 mg%** are often associated with severe intoxication, potentially life-threatening complications, and significant impairment of both motor and cognitive functions.

## **Correct Answer:** C. 300.