Answer:
Option (a).
Step-by-step explanation:
RNA is present as genetic material in some viruses only. RNA contains the nitrogenous bases ( adenine, thymine, uracil and cytosine), oxyribose sugar and the phosphate group.
RNA has uracil instead of thymine that pairs with adenine. RNA may have the extended base pair region complementarity but they do not have the ability to adopt the helical confirmation similar to the B- DNA.
Thus, the correct answer is option (a).