Which of these would have the greatest diversity of sequences?

(A) Greatest diversity of sequences would be observed in genomic library irrespective of the tissue it is made from.

(B) Both the genomic DNA libraries(muscle, brain) will almost completely overlap in my opinion.

The sequence obtained from human brain cDNA library would be completely overlapping to the genomic library made from human brain tissue and similarly, sequence obtained from human muscle tissue cDNA library would be completely overlapping the human muscle tissue genomic library.

In cDNA libraries, house keeping genes are constant only the tissue specific genes are different and hence these libraries will partially overlap.