## **Core Concept**
Rickets is a disease caused by vitamin D deficiency, leading to softening of bones in children. It affects bone mineralization, leading to skeletal deformities. Early manifestations are crucial for diagnosis and treatment.

## **Why the Correct Answer is Right**
The correct answer, **Cupping and fraying of metaphysis**, represents early radiological signs of rickets. These changes occur due to defective mineralization of the growth plate cartilage and the metaphyseal bone. The growth plates, or physis, are areas of cartilage near the ends of bones where bone growth occurs. In rickets, the normal process of calcification and bone formation is impaired, leading to characteristic radiographic findings.

## **Why Each Wrong Option is Incorrect**
- **Option A:** While bowing of legs (genu varum or genu valgum) is a clinical manifestation of rickets, it is not an early sign but rather a later complication.
- **Option B:** Osteopenia, or decreased bone density, can be seen in rickets but is not specific or an early manifestation.
- **Option D:** Delayed closure of fontanelles can be a sign of rickets, reflecting impaired bone mineralization. However, it is not as specific or early a sign as cupping and fraying of the metaphysis.

## **Clinical Pearl / High-Yield Fact**
A key clinical pearl is that rickets can present with a variety of symptoms, but early diagnosis often relies on radiographic findings. **Cupping and fraying of the metaphysis** are among the earliest and most specific radiographic signs, making them critical for the early diagnosis of rickets.

## **Correct Answer:** . Cupping and fraying of metaphysis