**Core Concept:** Gunshot injuries to the skull involve complex pathophysiology, including entry and exit wounds, trauma to the skull, and potential complications such as bullet fragments within the skull. The determination of the range of firing is crucial for forensic analysis.

**Why the Correct Answer is Right:**

Correct Answer: D. Depth of the entry wound (in cm)

Explanation: In a gunshot injury scenario, depth of the entry wound is a key factor to calculate the range of firing. A deeper entry wound indicates a closer firing distance, while a shallower wound suggests a greater distance.

**Why Each Wrong Option is Incorrect:**

A. Width of the entry wound (in cm): This parameter is less reliable compared to depth, as it can be affected by skull thickness and wound size.

B. Width of the exit wound (in cm): Width is influenced by skull thickness, making it less accurate in estimating firing distance.

C. Bullet fragments size: Although the size of bullet fragments provides evidence, it does not directly correlate with the firing distance, as it is influenced by various factors including bullet type, velocity, and path of the bullet.

**Why the Bullet Track:** The bullet track refers to the path the bullet took through the skull. Although it provides context about the trajectory, it does not directly determine the firing distance.

**Clinical Pearl:** In forensic investigations of gunshot injuries, the depth of the entry wound (option D) is the most reliable parameter to estimate the range of firing, as it is less affected by skull thickness and wound size. However, it is essential to consider all available evidence, including bullet fragments and the bullet track, for a comprehensive analysis.