Homeotic Genes Contain a Homeobox Sequence That Is Highly Conserved

Homeotic genes contain a homeobox sequence that is highly conserved among very diverse species.The homeobox encodes a protein domain that binds to DNA to regulate development of the embryo.The selective expression of homeotic genes,over time and space,is central to pattern formation during development.Based on this information,which of the following statements would you expect to be correct?

A) Homeotic genes are selectively expressed over space and time during development.
B) A homeobox-containing gene has to be a developmental regulator.
C) Homeoboxes cannot be expressed in nonhomeotic genes.
D) All organisms must have homeotic genes.