A D-aldotetrose on oxidation with concentrated HNO₃ resulted in optically inactive dicarboxylic acid. The structure of the D-aldotetrose is:

Step-by-step solution

For a carbohydrate to be classified as a D-sugar, the hydroxyl ( -OH ) group on the lowest chiral carbon (C3 in the case of an aldotetrose) must be on the right side in its Fischer projection. This eliminates options (A) and (B), which are L-sugars. Oxidation of an aldotetrose with concentrated HNO₃ converts both the aldehyde ( -CHO ) group at C1 and the primary alcohol ( -CH₂OH ) group at C4 into carboxylic acid ( -COOH ) groups, yielding a dicarboxylic acid (tartaric acid). The problem states that the resulting d