The carbohydrate "Ribose" present in DNA, is A. A pentose sugar B. present in pyranose from C. in "D" configuration D. a reducing sugar, when free E. in $$\alpha$$-anomeric form Choose the correct answer from the options given below:

The sugar unit present in DNA is $$\mathbf{2\text{-}deoxyribose}$$.

Step 1: Count of carbon atoms.
2-Deoxyribose contains five carbon atoms, so it is a pentose. ⇒ Statement A is correct.

Step 2: Ring size in nucleic acids.
Inside DNA the sugar occurs as a five-membered $$\mathbf{furanose}$$ ring, not a six-membered pyranose ring. ⇒ Statement B is incorrect.

Step 3: Absolute (D/L) configuration.
Naturally occurring ribose and deoxyribose possess the configuration related to $$\mathbf{D\text{-}glyceraldehyde}$$. ⇒ Statement C is correct.

Step 4: Reducing property when free.
A sugar is reducing if it has a free hemiacetal (aldehyde) group. Free 2-deoxyribose has such a group, so it reduces Tollens’ and Fehling’s reagents. ⇒ Statement D is correct.

Step 5: Anomeric configuration in DNA.
The base is attached to the anomeric carbon through a $$\mathbf{\beta}$$-N-glycosidic bond. Hence the sugar in DNA is the $$\beta$$-anomer, not the $$\alpha$$-anomer. ⇒ Statement E is incorrect.

Collecting the correct statements: A, C and D.

Therefore the correct option is Option B.