Linnaeus lived hundreds of years before scientists discovered DNA, genes, and the roles of DNA and genes in determining the traits of organisms. How have discoveries about DNA and genes affected scientific classification?

A. The discoveries confirmed all of the classifications that Linnaeus proposed, and no revisions have been necessary.
B. The discoveries confirmed all of the classifications that were based on observable traits, and no revisions have been necessary.
C. Although the discoveries did not confirm some of the classifications that were based on observable traits, scientists did not revise the older classifications.
D. The discoveries confirmed many but not all of the classifications that were based on observable traits, and scientists revised classifications when necessary.