As pregnancy progresses, the likelihood of a fetus becoming infected with toxoplasmosis:

As pregnancy progresses, the risk of a fetus contracting toxoplasmosis does indeed increase. This is due to several factors related to the development of the placenta and the immune response during pregnancy. In the early stages of pregnancy, a mother's immune system is somewhat more adept at filtering out infections. However, as the pregnancy advances, the placenta's permeability changes, and the mother's immune system adapts, which can allow pathogens, including Toxoplasma gondii, to cross more easily into the fetal environment.

Research shows that while the overall risk of transmission of the infection is lower in the first trimester, when transmission does occur during this period, it may lead to more severe fetal complications. In the later trimesters, the likelihood of transmission increases, and while the complications may be less severe, the increasing chances of transmission make the overall risk greater, leading to potential issues in the developing fetus. Thus, the correct choice reflects the understanding that as pregnancy progresses, so too does the risk of fetal infection with toxoplasmosis.