**Core Concept**
Sickle cell crisis is a complication of sickle cell disease, characterized by episodes of intense pain, often in the bones, due to the abnormal sickling of red blood cells. This phenomenon is primarily caused by the polymerization of deoxyhemoglobin S, leading to vaso-occlusion and ischemia in various organs, including the bones.

**Why the Correct Answer is Right**
The correct answer is related to the pathophysiological mechanism of sickling in the bone. In sickle cell crisis, the sickling of red blood cells leads to a cascade of events, resulting in vaso-occlusion and ischemia in the bone marrow. This ischemia causes a release of chemical mediators and cytokines, leading to inflammation and pain. The bone pain in sickle cell crisis is primarily due to the ischemia and inflammation of the bone marrow, rather than any direct damage to the bone itself.

**Why Each Wrong Option is Incorrect**
* **Option A:** Although vasculitis is a cause of bone pain, it is not the primary mechanism in sickle cell crisis. Vasculitis involves inflammation of the blood vessels, which is not the primary pathophysiological mechanism in sickle cell disease.
* **Option B:** Infection is a secondary complication of sickle cell crisis, but it is not the primary cause of bone pain. Infection can occur due to the compromised immune system in patients with sickle cell disease, but it is not directly related to the pathophysiology of sickle cell crisis.
* **Option D:** Osteomyelitis is a possible complication of sickle cell disease, but it is not the primary cause of bone pain in sickle cell crisis. Osteomyelitis involves direct infection of the bone, which is not the primary mechanism in sickle cell disease.

**Clinical Pearl / High-Yield Fact**
It's essential to recognize that sickle cell crisis can manifest as bone pain, but the pain is often out of proportion to the radiographic findings. This clinical correlation should be remembered, as it can help in differentiating sickle cell crisis from other causes of bone pain.

**Correct Answer: C. Ischemia and inflammation of the bone marrow.**