The genome of the pufferfish, Fugu rubripes, is only one-tenth the size of mammalian genomes. Which of the following most likely accounts for this difference? Choose one: A. movement of mobile genetic elements B. an imbalance in the rate at which DNA sequences are gained and lost C. horizontal gene transfer D. exon shrinkage E. elimination of introns

The correct answer will be option-E

Explanation:

The Tigerfish (Fugu rubripes) separated from the humans about 450 million years ago in the course of evolution and studied have shown that the genome of the Tigerfish contains only 365 million base pairs which are only one-tenth of the human genome.

Although both human and Tigerfish are vertebrates their genomes are so different as the genome of the fish contained only conserved gene structure with small intronic sequences and less repetitive sequence which is not the case of the human genome. The human genome contains highly repetitive sequence and the introns which so not code.

Thus, option-E is the correct answer.