**Core Concept**
Caisson's disease, also known as decompression sickness, is a condition that occurs when a person surfaces too quickly from a deep dive, resulting in the formation of gas bubbles in their bloodstream and tissues. This condition can cause a variety of symptoms, including joint pain.

**Why the Correct Answer is Right**
The joint pain in Caisson's disease is primarily caused by the formation of gas bubbles in the synovial fluid, which is the fluid that lubricates the joints. The bubbles can cause inflammation and damage to the joint tissues, leading to pain. The pain is typically felt in the larger joints, such as the knees, elbows, and shoulders.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not specifically address the pathophysiology of Caisson's disease.
**Option B:** This option is incorrect because it is a symptom of a different condition, such as osteoarthritis.
**Option C:** This option is incorrect because it is a treatment for joint pain, not a cause.

**Clinical Pearl / High-Yield Fact**
One important fact to remember is that Caisson's disease can be prevented by gradual decompression and the use of safety protocols when diving. It is also essential to recognize the symptoms of Caisson's disease, which can include joint pain, fatigue, and shortness of breath.

**Correct Answer:** C. Gas bubbles in synovial fluid.