In Fischer projection, D and L configurations are based on:
The orientation of the hydroxyl (-OH) group at the penultimate carbon is the scientifically accurate answer to this question. Within the study of Carbohydrates, this concept is well-established through extensive research and is documented in standard scientific literature. The specific properties, mechanisms, or characteristics of The orientation of the hydroxyl (-OH) group at the penultimate carbon directly address what is being asked. Among the other options, The rotation of plane-polarized light, The presence of an aldehyde or ketone group, and The number of chiral centers in the molecule d
Ref: Lehninger Principles of Biochemistry, Nelson & Cox, 8th Ed., Ch. 7
