Which statement about noncoding DNA is true?
a. Bacteria have the most noncoding DNA; more than 90% of their genome contains introns.
b. Noncoding DNA can only occur between genes, not within genes themselves.
c. Fruit flies are one of few organisms to have less coding DNA than humans.
d. Noncoding DNA refers to the proportion of base sequences in DNA that do not code for anything and seem to have no obvious purpose.
e. The role of noncoding DNA is understood to be extra genes that only get turned on in situations where the regular genes become damaged.