Which of the following is not an advantage of studying evolution through the use of DNA and proteins?

A) DNA and protein sequences follow simple rules of heredity.
B) Molecular sequence data are easy to obtain.
C) Molecular sequence data are amenable to quantitative analyses framed in the context of evolutionary genetics theory.
D) Researchers usually cannot obtain DNA or protein sequence data from extinct organisms.
E) Molecular sequence data allow researchers to investigate evolutionary relationships among organisms that are phenotypically very dissimilar.