SAT Subject Biology Practice Question 129: Answer and Explanation
Which individual is most likely to be a carrier of the trait in question?
Correct Answer: B
Individual II-4 does not exhibit the trait but has offspring who do. This means that he passed the allele for the trait to his offspring, with a likelihood of 100%, expressed as 1.0. Similar evidence is not available for the other individuals, making the likelihood that they are carriers less than 1.0.