**Core Concept**
Smokeless gunpowder is a type of propellant used in firearms, composed of a mixture of chemicals that produce a rapid release of gas when ignited. This reaction is based on the decomposition of nitrocellulose, a nitric acid ester of cellulose.

**Why the Correct Answer is Right**
Smokeless gunpowder is primarily composed of nitrocellulose, which is a polymer of cellulose that has been nitrated to increase its stability and explosive properties. When ignited, nitrocellulose undergoes a rapid decomposition reaction, releasing gases such as carbon dioxide, water vapor, and nitrogen. This reaction is highly exothermic, producing a rapid expansion of gases that propels the projectile out of the barrel.

**Why Each Wrong Option is Incorrect**
**Option A:** Not a component of smokeless gunpowder.
Smokeless gunpowder is not composed of potassium nitrate, which is a component of black powder, a different type of propellant.

**Option B:** Not a primary component.
While nitroglycerin is a highly explosive liquid, it is not a primary component of smokeless gunpowder.

**Option C:** Not a correct composition.
Smokeless gunpowder is not composed of a mixture of nitrocellulose and potassium nitrate.

**Clinical Pearl / High-Yield Fact**
Smokeless gunpowder is a critical component of modern firearms, and its properties are carefully controlled to ensure safe and efficient operation.

**Correct Answer:** C. Nitrocellulose.