## **Core Concept**
Edema in infants, particularly when described as being characterized by involvement of the hands and feet, can be associated with various conditions. One key condition to consider is **nephrotic syndrome**, but in the context of infants and specific involvement of hands and feet, **mucopolysaccharidosis** or other metabolic disorders might also present with edema. However, a classic condition that presents with edema of the hands and feet among other symptoms is **mucopolysaccharidosis type I (Hurler syndrome)**.

## **Why the Correct Answer is Right**
The correct answer, **C. Mucopolysaccharidosis**, is right because Hurler syndrome, a type of mucopolysaccharidosis, presents with a variety of symptoms including coarse facial features, clouded corneas, hepatosplenomegaly, and importantly, **stiff joints and edema of the hands and feet**. This condition results from a deficiency of the enzyme **alpha-L-iduronidase**, leading to accumulation of glycosaminoglycans (GAGs) in various tissues.

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option is incorrect because, without specification, it's hard to directly relate it to the condition described; common causes of edema in infants include heart failure, nephrotic syndrome, and liver disease, but these are not specifically linked to hand and foot edema in a distinctive way.
- **Option B:** Similarly, this option lacks specificity but might relate to infections or allergic reactions; these conditions can cause edema but are not characteristically associated with edema limited to hands and feet in infants.
- **Option D:** This option might relate to another metabolic or genetic condition but is not specifically known for causing edema of the hands and feet as a hallmark.

## **Clinical Pearl / High-Yield Fact**
A key clinical pearl is that **mucopolysaccharidosis type I (Hurler syndrome)** presents not only with developmental delays and physical abnormalities but also distinctive features such as **edema of the hands and feet**, which can be a critical clue for early diagnosis. Early recognition allows for early intervention, including enzyme replacement therapy.

## **Correct Answer:** . C. Mucopolysaccharidosis