One Piece of Evidence Suggesting That HOM and Hox Genes

One piece of evidence suggesting that HOM and Hox genes are homologous is

A) that the mouse has twice as many Hox gene clusters as DrosophilA.
B) that the homeobox identifies the portion of the genome involved in pattern formation.
C) that the homeobox has been identified in primitive organisms.
D) their linear order of organization on chromosomes is the same in mouse and Drosophila.