Which Carbon Atom of a Pentose Sugar Determines Whether It

Question

Which carbon atom of a pentose sugar determines whether it has a D or an L configuration?
A) carbon 1
B) carbon 3
C) carbon 4
D) carbon 5

Accepted Answer

The D or L configuration of a pentose sugar is determined by the orientation of the hydroxyl group (-OH) on the chiral carbon furthest from the carbonyl group, which, in pentoses, is carbon 4.