**Core Concept**
Chronic radiation pneumonitis is a fibrotic reaction of the lung tissue following radiation therapy, leading to pulmonary fibrosis. The characteristic histological finding is a result of the body's attempt to repair damage caused by radiation to the lung tissue.

**Why the Correct Answer is Right**
The characteristic histological finding of chronic radiation pneumonitis is the presence of **diffuse alveolar damage** and **fibrosis**. This is due to the activation of fibroblasts and the deposition of collagen in the lung tissue. The radiation causes damage to the alveolar epithelium and the endothelium, leading to an influx of inflammatory cells and the eventual deposition of collagen, resulting in fibrosis.

**Why Each Wrong Option is Incorrect**
* **Option A:** Intrapulmonary hemorrhage is not a characteristic histological finding of chronic radiation pneumonitis, although it may be seen in acute radiation pneumonitis.
* **Option B:** Chronic radiation pneumonitis is not typically characterized by the presence of granulomas, which are more commonly seen in conditions such as sarcoidosis.
* **Option C:** While radiation can cause damage to the lung tissue, the characteristic histological finding of chronic radiation pneumonitis is not the presence of cancer cells, which would be more indicative of a malignant process.

**Clinical Pearl / High-Yield Fact**
Chronic radiation pneumonitis can be a late complication of radiation therapy, occurring months to years after treatment. It is essential to recognize the characteristic histological findings to differentiate it from other pulmonary conditions.

**Correct Answer:** C.