Question

what best describes the role of genes in evolutionary classification?
a differences in the transcription of genes are used to define clades.

b certain genes are derived characters that can be used to define clades.

c the number of genes per organism helps scientists classify species in clades.

d gene comparisons are useful for excluding species from clades, but not for including them.

Explanation:

Evolutionary classification using genes relies on identifying shared derived genetic characters (synapomorphies) that define monophyletic clades. Differences in transcription (A) are not the primary basis, gene count (C) does not determine clade membership, and gene comparisons are used for both including and excluding species (D is incorrect).

Answer:

B. Certain genes are derived characters that can be used to define clades.