A genomic researcher is analyzing the genome of different species of raptors. She finds that a particular sequence in the Bald Eagle genome is identical to a sequence found in the Red Tailed Hawk, while most other sequences in those two genomes differ at many nucleotides. (The most recent common ancestor between Bald Eagles and Red Tailed Hawks was approximately 6.8 million years ago, which is plenty of time for mutation to generate DNA sequence variation.) Which of the following could explain the identical sequence in these otherwise differing genomes? a. The sequence encodes a protein critical for the production of feather color.
b. The sequence encodes a gene that is critical for life and cannot be easily mutated while retaining function.
c. The sequence is from an intron of a gene that encodes a protein in connective tissue.
d. None of these

d. None of these  

Explanation:

Probably the identical sequence found in both species is an ultraconserved sequence.

An ultraconserved element is a particular DNI sequence that remains exactly the same through evolution, with almost no modification, and that is shared by at least two completely different species.

These ultraconserved DNI portions seem to be highly essential for life. However, their function could not be determined yet. Most of them do not codify for proteins, but they could play a significant role in gene regulation.

It is suggested that these sequences are so significant for life that only a small change would compromise the organism´s aptitude.

the sugar-phosphate backbone forms the structural framework of nucleic acids, including dna and rna. this backbone is composed of alternating sugar and phosphate groups, and defines directionality of the molecule.