Imagine a genomic researcher who is analyzing the genome of different types of cats. she finds that a particular sequence in the north american bobcat genome is exactly identical to a sequence found in the common house cat, while most other sequences in those two genomes differ at many nucleotides. (the most recent common ancestor between bobcats and house cats is estimated to be about 6.8 million years, plenty of time for mutation to generate dna sequence variation.)
how can the identical sequence in these otherwise differing genomes be explained?
explain in detail

The options available for this question are :The sequence is from an intron of a gene that encodes a muscle protein.

The sequence is contained in a retrovirus that has infected both species.

The sequence encodes a gene that is critical for life and cannot be easily mutated while retaining function.

The sequence encodes a protein critical for the production of fur color.

The correct options are:

The sequence is contained in a retrovirus that has infected both species.

The sequence encodes a gene that is critical for life and cannot be easily mutated while retaining function.

Explanation:

Almost all organisms will have some genes in common because these genes will code for some important life processes which occur in every living being. These genes do not get mutated as they are present in common. These genes have nothing to do with the genetic variations.

Secondly, the genes in both the cats might be similar because a retrovirus might have infected both the cats. Viruses can incorporate their DNA into the host genome, so this is a possibility.

c. earths continental crust is thicker than its lithosphere.

because, the lithosphere is the outermost layer of the earth/ 100 km thick and is defined by its machanical properties.the lithosphere contains oceanic and continental crust that varies in age and thickness across locations and geologic time. the lithosphere is the coolest layer of the earth in terms of temperature. the term lithosphere should not be confused with the use of "geosphere" which is used to indicate all of earth systems, including the atmosphere, hydrosphere   and biosphere. the surface of the earth can be divided into the continental crust and the oceanic crust.   the continental crust is made mostly of granite while the oceanic crust is made of basalt. the average thickness of the continental crust is 25 miles and the average thickness of the oceanic crust is 5 miles.   three types of rock, igneous, sedimentary, and metamorphic, make up the surface of the earth. that's why 3 option is preferable.

just finished the test, the answer is d, greg is the least cost-effective because he charges the most for the project