Final answer:
Microcephaly can be caused by several infections grouped under the TORCH acronym, with congenital Rubella being a particularly notorious cause due to its severe teratogenic effects when contracted during pregnancy.
Step-by-step explanation:
Microcephaly is associated with congenital infections that are grouped under the acronym TORCH, where each letter stands for a particular infection. The infections included in the TORCH complex that can cause congenital microcephaly are Toxoplasmosis, Rubella, Cytomegalovirus (CMV), and Herpes simplex virus (HSV).
Out of the options provided, Toxoplasmosis caused by the protozoan parasite Toxoplasma gondii, Rubella caused by the rubella virus, and CMV caused by the cytomegalovirus are all known to be associated with microcephaly when transmitted congenitally. However, Rubella is especially notorious for causing severe congenital defects, including microcephaly, if a woman is infected during pregnancy. Based on the severity and the higher risk of congenital defects, Rubella would be the most likely cause of congenital microcephaly among the options listed.