Final answer:
Transmission of Toxoplasma gondii among mammals occurs through transplacental transmission from mother to fetus, not by casual or sexual contact.
Step-by-step explanation:
The question you're asking relates to the transmission pathways of Toxoplasma gondii, a parasitic protozoan that causes toxoplasmosis. Among the options provided, the correct mode of transmission for T. gondii among all mammals, including humans, is B. Transplacental transmission. This means that the parasite can be transmitted from an infected mother to her fetus during pregnancy, potentially leading to serious birth defects or other health issues for the unborn child.
While T. gondii can be transmitted in various ways, including through contaminated food, water or soil, or from undercooked meat, casual contact and sexual contact are not typical methods for transmitting this particular pathogen. It is important for pregnant women to be aware of the risks associated with toxoplasmosis, especially when coming into contact with environments that could be contaminated by cat feces, as domestic cats can shed T. gondii oocysts in their feces.