## **Core Concept**
Toxoplasmosis is a parasitic infection caused by *Toxoplasma gondii*, which can be transmitted from mother to fetus during pregnancy, leading to congenital toxoplasmosis. The risk of transmission increases with gestational age, but the severity of fetal infection is higher when transmission occurs early in pregnancy.

## **Why the Correct Answer is Right**
The risk of transmitting *Toxoplasma gondii* from mother to fetus increases as pregnancy progresses. However, the question revolves around the risk to the present baby given that the mother has ocular toxoplasmosis and is 10 weeks pregnant. Ocular toxoplasmosis in the mother typically indicates a chronic infection. The risk of vertical transmission at 10 weeks gestation is lower compared to later in pregnancy, but since the mother likely has a chronic infection, the risk to the fetus is still present. The exact risk percentage varies, but generally, the risk of transmission at 10 weeks is around 10-15%.

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option suggests a 0% risk, which is incorrect because there is always a risk of transmission from mother to fetus, even if the mother has chronic infection.
- **Option B:** This option might suggest a risk higher than what is generally accepted for 10 weeks gestation.
- **Option D:** This option suggests a risk that might be higher than what is typically observed for the given gestational age.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that the risk of congenital toxoplasmosis transmission increases with gestational age, but the severity of the disease in the fetus is greater if infection occurs early in pregnancy. Serological screening for toxoplasmosis is recommended in pregnant women to identify those at risk.

## **Correct Answer:** .