## **Core Concept**
Congenital toxoplasmosis occurs when *Toxoplasma gondii* infects a fetus during pregnancy, potentially leading to serious health issues. The manifestations of congenital toxoplasmosis can vary widely, but certain symptoms are more commonly observed. This question tests knowledge of the typical presentations of congenital toxoplasmosis.

## **Why the Correct Answer is Right**
The correct answer, **chorioretinitis**, is the most common manifestation of congenital toxoplasmosis. This condition involves inflammation of the choroid and retina in the eye, often leading to vision impairment. *Toxoplasma gondii* has a particular affinity for the retina, and congenital infection frequently results in ocular involvement, with chorioretinitis being a hallmark finding.

## **Why Each Wrong Option is Incorrect**
- **Option A:** While **asymptomatic infection** can indeed occur in congenital toxoplasmosis, with some infected infants not displaying any obvious symptoms at birth, it is not the most common manifestation that is clinically apparent or reported.
- **Option B:** **Hydrocephalus** can be a manifestation of congenital toxoplasmosis due to the infection's impact on the central nervous system, but it is not the most common presentation.
- **Option C:** This option is actually the correct answer but let's evaluate the rest for thoroughness.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that congenital toxoplasmosis can often present with a classic triad of findings: chorioretinitis, hydrocephalus, and intracranial calcifications. However, not all infants will exhibit all three. Chorioretinitis, being the most common and frequently the only manifestation, makes regular ophthalmologic screening crucial for infants at risk.

## **Correct Answer:** D. Chorioretinitis