<span>The position of the carbonyl group.
Both aldoses and ketoses are monosaccharides. They are simple sugars with a Carbon chain. The difference is what's in the position of the carbonyl group: aldoses have an aldehyde group while ketoses have aketone group.</span>
Its the reverse
5'CGCTAA 3'
3'AATCGC 5'
Option C. Organisms were probably more complex during past eras.