I believe the best description comparing the structure of carbohydrates and nucleic acids would be A.
4. Isotopes of the same element
The 2-bromo-1-chloro-2-methylpropane molecule contains a total of 14 atom(s). There are 4 Carbon atom(s), 8 Hydrogen atom(s), 1 Chlorine atom(s) and 1 Bromine atom(s). A chemical formula of 2-bromo-1-chloro-2-methylpropane can therefore be written as C4H8BrCl. Is it also commonly called as Propane.