The allele for brown eyes is dominant to the allele for blue eyes. Which of the following best explains how two brown-eyed parents could produce a blue eyed child?
A-- One parent must be carrying the recessive allele for blue eyes.
B-- One parent must have had only blue eyed parents.
C-- Mutations after fertilization could alter gene sequences and change alleles.
D-- Each parent must be carrying the recessive allele for blue eyes.

Cladistics is a way of classifying organisms by examining the characteristics of their ancestors and descendants and depicting the relationships in a cladogram. which of the following best describes a challenge in classifying organisms this way? a. there are millions of species on earth, and a cladogram is not a practical means for classifying all of them. b. it is impossible to tell which organisms are most closely related to each other using a cladogram. c. cladograms are detail-oriented and do not provide a useful understanding of evolutionary relationships. d. there is a limited number of ways to organize the information, so most cladograms end up looking very similar.