**Core Concept**
The composition of black gunpowder, also known as gunpowder or nitrocellulose, is crucial in forensic medicine for identifying and analyzing explosive residues. The traditional composition of black gunpowder consists of a specific ratio of charcoal, potassium nitrate, and sulfur.

**Why the Correct Answer is Right**
The correct composition of black gunpowder is charcoal 15%, potassium nitrate 75%, and sulfur 10%. This specific ratio is essential for the controlled combustion of gunpowder, producing a consistent and predictable burn rate. The charcoal provides a fuel source, while the potassium nitrate acts as an oxidizer, facilitating the combustion process. The sulfur helps to lower the ignition temperature and increase the burn rate. The precise ratio of these components enables the controlled release of energy, which is critical in firearms and explosive devices.

**Why Each Wrong Option is Incorrect**
**Option A:** This composition is incorrect because it contains a higher percentage of charcoal (60%) and a lower percentage of potassium nitrate (20%), which would result in an uncontrolled and potentially explosive burn rate.

**Option B:** This composition is incorrect because it contains a lower percentage of charcoal (25%) and a higher percentage of potassium nitrate (70%), which would lead to a slow and incomplete combustion process.

**Option D:** This composition is incorrect because it contains a higher percentage of charcoal (65%) and a lower percentage of potassium nitrate (20%), which would result in an uncontrolled and potentially explosive burn rate.

**Clinical Pearl / High-Yield Fact**
In forensic medicine, the analysis of black gunpowder residues is crucial in identifying and linking firearms to crime scenes. The presence of specific gunpowder particles, such as those containing potassium nitrate, can be used to reconstruct the trajectory of a gunshot wound and identify the type of firearm used.

**✓ Correct Answer: C. Charcoal 15% + Potassium nitrate 75% +- sulphur 10%**