D. both plants and animals need freshwater to live
Birds have hollow bones due to the fact thay need to be as light as possible for their wings to generate enough lift for them to fly
The monomer units of the carbohydrates vary in their total numbers extensively. Moreover, positions of the carbonyl groups along with the orientation of the hydroxyl groups also vary in the carbohydrates' monomers. The presence of any modification is also variable.
On the other hand, the nucleic acids have only 4 monomeric units. The linkages between the nucleic acid residues have less geometry than the glycosidic linkages.
The correct answer is option A,
Reason - The density of outer core is less than the density of inner core density and thus among all the given options the more probable answer is option A
