Which of the following structures represents -D-ribulofuranose?

Step-by-step solution

Ribulose is a ketopentose, meaning it is a 5-carbon sugar with a ketone group at C2. A furanose ring is a 5-membered cyclic hemiacetal. For a ketopentose, this ring forms by the reaction of the C5 hydroxyl group with the C2 carbonyl group. Let us analyze the given options. Options (A) and (D) are cyclic Fischer projections of aldopentoses, as their anomeric carbons (C1) have a hydrogen atom attached. Option (C) is a Haworth projection of a ketohexose. It contains 6 carbon atoms in total (4 in the furanose ring and