Answer:
a. hox genes.
Step-by-step explanation:
HOX genes have the following functions:
- HOX genes are the homeobox subset.
- They specify the areas of the embryo's body plan along the animal head-tail axis.
- They are encoding Hox proteins that specify the position characteristics and ensure that the right structures form at the right position in the body.
- They regulate high-level executive genes, such as transcription factors and intracellular signaling molecules, which adhere, number, form, and growth to cells.
The vertebrates are highly preserved.
The clusters and other genes occur uninterrupted.
Evolutionary, the heterogeneous regulatory areas between the genes most previously present are larger and more preserved than those present at the other ends of the clusters.
The characteristical feature is that these are homeodomain proteins with a highly preserved area of DNA binding encoded with homeobox gens.