**Core Concept:** Metastatic calcification is a pathological process characterized by the deposition of calcium salts in soft tissues. It can lead to tissue hardening and is typically seen in conditions with hypercalcemia or hyperphosphatemia, or both.

**Why the Correct Answer is Right:**
Metastatic calcification is commonly observed in conditions like primary hyperparathyroidism, chronic renal failure, and certain medications (e.g., calcitriol). In these situations, the elevated calcium and/or phosphate levels in blood lead to calcium deposition in tissues, causing the clinical signs and symptoms associated with this process.

**Why Each Wrong Option is Incorrect:**
A. Hypercalcemia might be present in conditions like hypercalcemia of malignancy or other malignancies, but the correct answer highlights that calcification is not typically seen in these cases.
B. Hyperphosphatemia can lead to calcification, as seen in chronic renal failure, but the correct answer emphasizes that calcification is not absent in this condition.
C. Chronic renal failure is mentioned as an example of a condition with calcification, so this option is not incorrect but merely supplementary to the correct answer.
D. Calcification can occur in conditions like sarcoidosis or scleroderma, but the correct answer highlights that calcification is not absent in these cases.

**Clinical Pearl:**
The clinical pearl here is to differentiate between primary and secondary hyperparathyroidism, as the presence of calcification distinguishes between the two conditions. Primary hyperparathyroidism is usually associated with calcification, while secondary hyperparathyroidism is not.

**Correct Answer:** C. Chronic renal failure

**Explanation:** In chronic renal failure, elevated phosphate levels and reduced renal phosphate excretion lead to increased phosphate deposition in soft tissues, causing calcification. This is distinct from primary hyperparathyroidism, where hypercalcemia is the primary issue and calcification is more likely to occur.