**Core Concept:**
The question tests our knowledge about the normal range of serum calcium levels in the body, which is essential for maintaining proper bone mineralization and neuromuscular and cardiovascular functions. Calcium is regulated by the parathyroid hormone (PTH), calcitonin, and vitamin D.

**Why the Correct Answer is Right:**
The normal range of serum calcium levels is between 8.5 and 10.2 mg/dL (2.14 to 2.55 mmol/L). This is maintained by the coordinated action of parathyroid hormone (PTH), calcitonin, and vitamin D. PTH elevates calcium levels through increased renal reabsorption, increased intestinal calcium absorption, and bone resorption, while calcitonin lowers calcium levels by promoting calcium excretion, inhibiting renal calcium reabsorption, and antagonizing PTH. Vitamin D promotes calcium absorption in the intestines.

**Why Each Wrong Option is Incorrect:**
A. Option A is incorrect because the correct answer lies within the given range.
B. Option B is incorrect because the correct answer is within the normal range.
C. Option C is incorrect because the correct answer is within the normal range.

**Clinical Pearl:**
A decrease in serum calcium levels can lead to hypocalcemia, causing symptoms such as tetany, convulsions, or even seizures, while an increase in serum calcium levels results in hypercalcemia, which can cause nephrolithiasis, nephrocalcinosis, or even renal insufficiency. Maintaining calcium levels within the normal range is vital for overall health and organ function.