Final answer:
The true statement about vertebrate Hox genes is that they are expressed in an anterior-to-posterior pattern that corresponds to the chromosomal position of the genes within the Hox cluster, option 1).
Step-by-step explanation:
Out of the given statements, the true statement about vertebrate Hox genes is that vertebrate Hox genes are expressed in an anterior-to-posterior pattern that corresponds to the chromosomal position of the genes within the Hox cluster. Option 1) is correct naswer. This means that the expression of Hox genes follows a specific pattern along the body axis, from the head (anterior) to the tail (posterior), based on their position in the cluster on the chromosome. The other statements are not true: vertebrate Hox genes do contain the homeobox DNA sequence like in invertebrate homeotic genes, vertebrate Hox genes are not examples of housekeeping genes that are constitutively expressed, and vertebrate Hox genes are arranged in clusters (Hox-A, Hox-B, Hox-C, and Hox-D) on different chromosomes, unlike in invertebrates.