Final answer:
The pedigree suggests the inheritance of an autosomal dominant disorder. Person 1 is likely to have a heterozygous genotype (Aa), giving them a 50% chance of having normal children. Person 3 also has a 25% chance of having normal children if their partner is unaffected (aa). Thus, the correct answer is a) Autosomal Dominant; Aa; 50%; 25%.
Step-by-step explanation:
To determine whether the pedigree represents the inheritance of an autosomal dominant or an autosomal recessive disorder, one must look at the pattern through which the disorder is manifested in subsequent generations. For autosomal dominant disorders, a single copy of the disease allele (A) can cause the disorder, meaning that the affected individual can have the genotype AA (homozygous dominant) or Aa (heterozygous), whereas unaffected individuals must be aa (homozygous recessive).
Given the information that person 1 has a 50% chance of having normal children, and person 3, who presumably is one of their children, has a 25% chance of having normal children, the pattern seems consistent with an autosomal dominant disorder. This is because, if person 1 is heterozygous (Aa), each child has a 50% chance of inheriting the dominant allele and being affected. If person 1 is homozygous dominant (AA), all of their children would be affected. Similarly, if person 3 is heterozygous (Aa), they would have a 50% chance of passing the disorder to their children; a 25% chance of normal children suggests person 3 is affected and their partner is unaffected (aa).
Based on these probabilities and inheritance rules, the best answer to the student's question is option a): Autosomal Dominant; Aa; 50%; 25%.