**Core Concept**
Congenital toxoplasmosis occurs when Toxoplasma gondii, a protozoan parasite, is transmitted from the mother to the fetus during pregnancy. This can lead to severe complications in the newborn, including neurological and ocular abnormalities.

**Why the Correct Answer is Right**
The correct answer is related to the mechanism of transmission. Toxoplasma gondii can be transmitted to the fetus through the placenta, but only if the mother is infected for the first time during pregnancy. If the mother is already immune to Toxoplasma gondii, the risk of transmission to the fetus is significantly reduced. This is because the mother's immune system produces antibodies that can cross the placenta and provide protection to the fetus.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is not related to congenital toxoplasmosis. It is a distractor and does not provide any relevant information about the topic.
* **Option B:** This option is incorrect because it implies that the risk of transmission is not related to the mother's immune status. However, the risk of transmission is significantly reduced if the mother is already immune to Toxoplasma gondii.
* **Option C:** This option is incorrect because it implies that the risk of transmission is not related to the timing of the mother's infection. However, the risk of transmission is significantly increased if the mother is infected for the first time during pregnancy.

**Clinical Pearl / High-Yield Fact**
To prevent congenital toxoplasmosis, pregnant women should avoid eating undercooked meat, especially pork and lamb, and should avoid contact with cat feces. They should also avoid changing cat litter and should wash their hands thoroughly after handling cats or their litter.

**Correct Answer:** B.