Answer: The correct option is B. Deoxyribose.
DNA is made up of small units called as dNTP ( deoxyribonucleoside triphosphate). In the dNTP, deoxyribose sugar, nitogenous base, and phosphate group is present. Deoxyribose is a pentose sugar, which contains Hydrogen group at 2' carbon of its pentose ring ( therefore called deoxyribose).
Whereas in RNA, OH ( hydroxyl group) is present at 2' carbon of the pentose ring. Therefore, it is not called deoxyribose.
Thus, deoxyribose is the structural component found in DNA but not in RNA.