Which Statement About Hox Genes Is True

Which statement about Hox genes is true?

A) In mammals, the temporal and spatial expression of Hox genes follows their linear order on the chromosome.
B) Most but not all Hox genes contain a sequence of DNA called the homeobox.
C) Hox gene products serve as structural proteins.
D) In vertebrates, Hox genes control differentiation primarily along the dorsal-ventral axis.
E) Mammals have ten Hox gene complexes, each with about four genes.