## **Core Concept**
The question involves a 9-year-old boy presenting with elevated both Prothrombin Time (PT) and activated Partial Thromboplastin Time (aPTT). This suggests a coagulopathy affecting both the intrinsic and extrinsic coagulation pathways, which are reflected in these tests. PT primarily assesses the extrinsic pathway, while aPTT evaluates the intrinsic pathway.

## **Why the Correct Answer is Right**
The correct answer, Vitamin K deficiency or a condition like Liver disease, affects both PT and aPTT because both tests rely on the proper functioning of clotting factors produced in the liver and vitamin K-dependent. Vitamin K is essential for the gamma-carboxylation of clotting factors II, VII, IX, and X, and proteins C and S. A deficiency in vitamin K or liver dysfunction leads to decreased production or function of these factors, resulting in prolonged PT and aPTT.

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option is not provided, but typically, conditions that affect only one pathway (e.g., factor VIII deficiency for intrinsic pathway) would not elevate both PT and aPTT.
- **Option B:** Similarly, without specifics, if an option suggests a condition primarily affecting one coagulation pathway, it would not be correct if both PT and aPTT are elevated.
- **Option D:** Without specifics on option D, if it suggests a condition not affecting both coagulation pathways (intrinsic and extrinsic), it would be incorrect.

## **Clinical Pearl / High-Yield Fact**
A key clinical pearl is that Vitamin K deficiency or liver disease can present with elevated PT and aPTT. Clinicians should consider these in the differential diagnosis for coagulopathy, especially in pediatric patients who may have dietary deficiencies or liver issues.

## **Correct Answer: C.**