Adog's sense of smell has improved since being domesticated because

a: they evolved to have a better sense of smell
b: they have adapted their sense of smell
c: humans have bred them to have a strong sense of smell
d: it was essential to their survival

Transposon can cause mutations in genes at or near the site of transposon insertion. it is possible for these elements to transpose away from their original site, causing a reversion of the mutant phenotype. in some cases, however, even more severe phenotypes appear when these elements excise from this site, due to events at or near the mutant allele. what might be happening to the transposon or the nearby gene to create more severe mutations?