**Core Concept**
A signature fracture of the skull is a characteristic type of injury resulting from a sharp object, often a gunshot or a sharp blow, that causes a depression in the skull bone. This type of fracture is typically associated with a specific mechanism of injury and is an important diagnostic clue in forensic pathology.

**Why the Correct Answer is Right**
A depressed fracture occurs when a sharp object penetrates the skull bone, causing a depression in the bone surface. The object's shape and size are often imprinted on the bone, resulting in a signature fracture pattern. This type of fracture is usually seen in cases of assault or gunshot wounds, where a sharp object has struck the skull. The object's shape and size are transferred to the bone, creating a unique pattern that can be used to identify the weapon used.

**Why Each Wrong Option is Incorrect**
**Option A:** Gutter fracture refers to a type of fracture that occurs when a blunt object strikes the skull, causing a linear or curved fracture. This type of fracture does not typically result in a signature pattern.
**Option C:** Ring fracture is a type of fracture that occurs around the foramen magnum, typically seen in cases of severe head trauma or skull base fractures. This type of fracture is not associated with a signature pattern.
**Option D:** Sutural separation refers to the separation of the sutures of the skull, typically seen in cases of infant or child abuse. This type of injury does not result in a signature fracture pattern.

**Clinical Pearl / High-Yield Fact**
In forensic pathology, the presence of a signature fracture can be an important clue in identifying the weapon used in a crime. The shape and size of the fracture can be matched to the shape and size of the object that caused the injury, providing valuable evidence in criminal investigations.

✓ Correct Answer: B. Depressed fracture