Pedigree analysis for earlobe genotypes

Steps:

• Determine phenotypes: free earlobes (dominant, F_) vs. attached (recessive, ff).
• Identify individuals with free earlobes who must carry f allele (heterozygous Ff) based on offspring.
• Check parents of attached-earlobe children: they must contribute f, so if free-lobed, they are Ff.
• Confirm for options: only 1 and 7 fit as free-lobed parents of ff offspring.

Why A is correct:

• Individuals 1 and 7 exhibit free earlobes but have ff children, requiring each to pass f, so both are Ff per Mendelian inheritance.

Why the others are wrong:

• B: 3 and 4 have only free-lobed offspring, allowing homozygous FF.
• C: 5 and 8 are ff (attached), so homozygous recessive.
• D: 6 and 9 lack ff offspring, allowing FF genotype.

Final answer: A