## Core Concept
Rickets is a disease caused by vitamin D deficiency, leading to softening and weakening of bones in children. It results from impaired mineralization of bone tissue due to lack of vitamin D, calcium, or phosphate. The condition is characterized by skeletal deformities and growth retardation.

## Why the Correct Answer is Right
The correct answer, **C. Cupping and fraying of metaphyses**, is right because in rickets, the growth plates (metaphyses) of bones show characteristic radiographic changes. These include cupping, fraying, and widening of the growth plates. Cupping refers to the concave appearance of the metaphyses, while fraying describes the irregular, fuzzy appearance of the metaphyseal margins. These changes are due to defective mineralization and are hallmarks of rickets.

## Why Each Wrong Option is Incorrect
- **Option A: Sclerotic metaphyses** - Sclerosis refers to an increase in bone density, which is not a feature of rickets. Instead, rickets is characterized by decreased bone density and defective mineralization.
- **Option B: Osteopenia of shaft** - While osteopenia (reduced bone mass) is indeed a feature of rickets, it is a more general finding and not as specific to rickets as the changes seen in the metaphyses.
- **Option D: Bone fragmentation** - Bone fragmentation can occur in various bone disorders but is not a defining characteristic of rickets.

## Clinical Pearl / High-Yield Fact
A key clinical pearl for rickets is that it can be caused not only by vitamin D deficiency but also by phosphate deficiency or impaired vitamin D activation. Clinicians should consider these alternative causes in patients with rickets-like symptoms.

## Correct Answer: C. Cupping and fraying of metaphyses