The pufferfish, Fugu rubripes, has a genome that is one-tenth the size of mammalian genomes.Which of the following statements is NOT a possible reason for this size difference?

A)Intron sequences in Fugu are shorter than those in mammals.
B)Fugu lacks the repetitive DNA found in mammals.
C)The Fugu genome seems to have lost sequences faster than it has gained sequences over evolutionary time.
D)Fugu has lost many genes that are part of gene families.