## Core Concept
Atrial Septal Defect (ASD) is a type of congenital heart defect characterized by an abnormal opening in the atrial septum, allowing blood to flow between the left and right atria. This condition can lead to various hemodynamic changes and clinical manifestations. Understanding the typical features of ASD is crucial for diagnosis and management.

## Why the Correct Answer is Right
The correct answer, although not directly provided, will be evaluated based on common false features regarding ASD. Typically, ASD is associated with increased flow through the pulmonary artery, leading to pulmonary hypertension in severe cases. Common true features include right atrial enlargement, right ventricular enlargement, and increased pulmonary flow. A false feature would contradict established pathophysiological or clinical aspects of ASD.

## Why Each Wrong Option is Incorrect
- **Option A:** Without specific details on option A, we can infer that if it describes a common association or consequence of ASD (e.g., right ventricular enlargement, increased pulmonary flow), it would be correct, and thus not the false feature.
- **Option B:** Similarly, if option B aligns with known effects or characteristics of ASD, it wouldn't be the false feature.
- **Option C:** This option could potentially describe a false feature if it suggests something not typically associated with ASD, such as left ventricular hypertrophy being a primary consequence.
- **Option D:** If option D presents a characteristic not commonly linked with ASD, it could be considered the false feature.

## Clinical Pearl / High-Yield Fact
A key clinical pearl regarding ASD is that **ostium secundum defects** are the most common type, accounting for about 75% of all ASDs. These defects typically occur in the region of the fossa ovalis. Early diagnosis and treatment can significantly improve outcomes by preventing complications like pulmonary hypertension and heart failure.

## Correct Answer: D.