**Core Concept**

Metastatic calcification is a type of calcification that occurs in tissues due to elevated levels of calcium in the blood, often as a result of hypercalcemia. This leads to the deposition of calcium salts in various organs and tissues, causing damage and dysfunction.

**Why the Correct Answer is Right**

Metastatic calcification is commonly seen in the kidneys, lungs, and stomach due to the high concentration of calcium in the blood. When calcium levels exceed the normal range, it can lead to the formation of calcium phosphate crystals in these tissues, causing damage and disrupting normal tissue function. This process is often seen in conditions such as hyperparathyroidism, where excess parathyroid hormone leads to increased calcium levels in the blood.

**Why Each Wrong Option is Incorrect**

* **Option A:** While dystrophic calcification can occur in damaged or necrotic tissues, it is not the same as metastatic calcification, which occurs due to elevated calcium levels in the blood.
* **Option B:** **Hyperplastic calcification** is not a recognized term in pathology, and calcification is not typically associated with hyperplasia.
* **Option C:** **Idiopathic** calcification would imply an unknown or unexplained cause, whereas metastatic calcification has a well-defined pathophysiological mechanism.

**Clinical Pearl / High-Yield Fact**

Metastatic calcification is often seen in conditions with elevated parathyroid hormone levels, such as primary hyperparathyroidism, and can be a marker for these conditions.

**Correct Answer: C.**