Final answer:
Mothers can pass AIDS to their unborn children through the placenta or during childbirth. Chickenpox can also be transmitted but not via breastmilk, and certain antibodies can be passed to infants to provide passive immunity shortly after birth. Vaccines prevent many of these infections and do not cause autism.
Step-by-step explanation:
Diseases Passed from Mother to Unborn Child:
The disease that mothers are thought to be able to pass to their unborn children from the options provided is b) AIDS. Diseases like AIDS can be transmitted from an infected mother to her child transplacentally, or through contact with contaminated body fluids including breastmilk. Not all viruses mentioned in the options necessarily have the same capacity for transmission to the unborn child.
For example, chickenpox (varicella) can be transmitted during pregnancy and may lead to birth defects or severe infection in newborns, but it's not transmitted via breastmilk. On the other hand, passive immunity can be conferred through antibodies passed from mother to infant, which can help protect against certain diseases shortly after birth. It's important to note that many infections can be prevented through vaccinations, which establish active immunity, and do not increase the risk of autism.