**Core Concept**
The child's physical characteristics, such as short stature, short webbed neck, and widely spaced nipples, are suggestive of Turner syndrome (45,X), a chromosomal abnormality affecting females. The cardiovascular system is often affected in Turner syndrome, with a specific anomaly being a common occurrence.

**Why the Correct Answer is Right**
In individuals with Turner syndrome, the cardiovascular anomaly most likely to be present is a bicuspid aortic valve. This is due to the abnormal development of the aortic valve leaflets, which can lead to aortic stenosis or regurgitation. The pathogenesis is thought to be related to the absence of one X chromosome, which affects the development of the aortic valve. The bicuspid aortic valve is a common congenital heart defect in Turner syndrome, occurring in approximately 30-50% of affected individuals. The presence of a bicuspid aortic valve can lead to complications such as aortic dilatation, aortic regurgitation, or even aortic dissection.

**Why Each Wrong Option is Incorrect**
* **Option A:** Coarctation of the aorta is a congenital heart defect characterized by narrowing of the aortic isthmus. While it can occur in Turner syndrome, it is not the most common cardiovascular anomaly associated with this condition.
* **Option B:** Ventricular septal defect (VSD) is a common congenital heart defect, but it is not specifically associated with Turner syndrome. VSD can occur in isolation or as part of a more complex congenital heart defect.
* **Option C:** Tetralogy of Fallot is a complex congenital heart defect characterized by four anatomical abnormalities. While it can occur in individuals with Turner syndrome, it is not the most common cardiovascular anomaly associated with this condition.

**Clinical Pearl / High-Yield Fact**
Turner syndrome is characterized by a high incidence of cardiovascular anomalies, with a bicuspid aortic valve being the most common. It is essential for clinicians to be aware of this association to provide appropriate screening and management for affected individuals.

**Correct Answer:** C.