In both DNA and RNA, heterocyclic base and phosphate ester linkages are at-

In the sugar of nucleic acids (ribose in RNA and 2-deoxyribose in DNA) the carbon atoms are numbered with a prime (') to distinguish them from the base carbons. The important positions are:

• $$C_1'$$ - the anomeric carbon that carries the hemi-acetal OH group in the free sugar.
• $$C_2'$$ - bears the OH group in ribose and H in 2-deoxyribose.
• $$C_3'$$ - has an OH group that participates in phosphodiester linkage within the polymer chain.
• $$C_5'$$ - is the terminal -CH2OH carbon that is not part of the furanose ring.

1. Attachment of the heterocyclic base (purine or pyrimidine):
The base forms an N-glycosidic bond with the anomeric carbon. Hence the linkage is at $$C_1'$$ of the sugar.

2. Attachment of the phosphate group:
The phosphate forms an ester with the terminal primary alcohol group on $$C_5'$$. This phosphate can further join to $$C_3'$$ of the next nucleotide to create the phosphodiester backbone, but its first attachment on an individual nucleotide is always at $$C_5'$$.

Because these positions are the same in both RNA and DNA, the heterocyclic base is linked to $$C_1'$$ and the phosphate to $$C_5'$$ in every nucleotide.

Therefore, the correct pair of linkages is $$C_1'$$ for the base and $$C_5'$$ for the phosphate ester.

Option C which is: $$C_1'$$ and $$C_5'$$ respectively of the sugar molecule