One of the Finest Available Sequences of Fossils Shows How

Multiple Choice

One of the finest available sequences of fossils shows how horses have changed slowly and by subtle steps from small, shrub-browsing ancestors to the large, grass-grazing modern horse. A large number of fossil species have been named, and it is often difficult to decide on the identity of a fossil horse because transitional forms are common. This record of evolution best fits the idea of

A) the gradual model of speciation.
B) punctuated equilibrium.
C) adaptive radiation.
D) hybrid breakdown.