Human Hox Genes Are in Four Clusters: HOXA, HOXB, HOXC

Multiple Choice

Human Hox genes are in four clusters: HOXA, HOXB, HOXC, and HOXD, for a total of 39 genes. Besides conserving the clustering of genes, evolution has also conserved __________.

A) their chromosomal locations
B) the order of the genes within them
C) their expression along the dorsal-ventral axis
D) the mutations to which they give rise
E) their bilateral symmetry