What conclusion is apparent from the data in the accompanying table?
A) Land animals have more Hox genes than do those that live in water.
B) All bilaterian phyla have had the same degree of expansion in their numbers of Hox genes.
C) Acoel flatworms should be expected to contain seven Hox genes.
D) The expansion in number of Hox genes throughout vertebrate evolution cannot be explained merely by three duplications of the ancestral vertebrate Hox cluster.
E) Extant insects all have seven Hox genes.