**Core Concept**
The patient's symptoms and physical examination findings suggest a congenital heart defect with left-to-right shunting, leading to pulmonary hypertension and eventual reversal of shunt.

**Why the Correct Answer is Right**
The patient's presentation is consistent with Tetralogy of Fallot (TOF), characterized by four classic components: ventricular septal defect (VSD), pulmonary stenosis, right ventricular hypertrophy, and an overriding aorta. The wide, fixed split S2 is due to the delayed closure of the pulmonary valve, while the ejection systolic murmur is related to the pulmonary stenosis. The left axis deviation on ECG is a result of the right ventricular hypertrophy. As the disease progresses, the left-to-right shunt can reverse, leading to cyanosis.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is not provided.
* **Option B:** This option is not provided.
* **Option C:** This option is not provided.
* **Option D:** This option is not provided. However, if a specific option were given, the explanation would follow.

**Clinical Pearl / High-Yield Fact**
In TOF, the degree of cyanosis is inversely related to the severity of pulmonary stenosis. Therefore, patients with more severe pulmonary stenosis may present with less cyanosis, making the diagnosis more challenging.

**Correct Answer: D. Tetralogy of Fallot**