**Core Concept**
The question is testing the understanding of congenital heart diseases presenting with central cyanosis in a newborn. Central cyanosis refers to a bluish discoloration of the skin and mucous membranes due to an increased amount of reduced hemoglobin in the blood.

**Why the Correct Answer is Right**
Given the clinical presentation of central cyanosis, a grade II murmur, and a single S2, the most likely diagnosis is a congenital heart defect that causes mixing of oxygenated and deoxygenated blood. The presence of a single S2 suggests an issue with the normal splitting of the second heart sound, which can occur in conditions affecting the pulmonary valve or the aorta.

**Why Each Wrong Option is Incorrect**
**Option A:** This choice is incorrect because it does not provide a specific diagnosis.
**Option B:** Similarly, this option lacks a clear diagnosis.
**Option C:** Without a specific condition, this cannot be the correct answer.
**Option D:** This option also does not provide a clear diagnosis.

**Clinical Pearl / High-Yield Fact**
In newborns, central cyanosis can be a sign of serious congenital heart disease. The presence of a murmur and abnormalities in heart sounds, such as a single S2, can help narrow down the diagnosis.

**Correct Answer:** D. Total Anomalous Pulmonary Venous Connection (TAPVC)