Final answer:
The chance of developing early-onset Alzheimer's for the woman, if she has the rare autosomal dominant allele, is 50%. If she has not been confirmed to carry the allele, the individual chance cannot be determined from the provided information.
Step-by-step explanation:
The chance that the woman will develop early-onset Alzheimer's based purely on the information given in the question is impossible to answer definitively without more context, such as her family history or genetic information. However, if we interpret the question to mean that the woman has inherited the rare autosomal dominant allele for early-onset Alzheimer's that accounts for 3% of all cases, then the answer would be c) 50%. This is because if she has inherited the allele from a parent who has the disease, there is a 50% chance that she received the allele considering that autosomal dominant diseases require only one copy of the allele to manifest.
If the woman has not been confirmed to carry the allele, then the percentage cannot be determined from the information provided, and this would be a misunderstanding of genetic risk percentages versus individual genetic makeup. The 3% refers to the proportion of all Alzheimer's cases, not the individual probability of any given person developing the disease. Without genetic testing, an individual's risk remains unknown.