Which of the following is/are true of diastereomers?

Diastereomers are a class of stereoisomers that possess multiple stereocenters but are not related as mirror images. Unlike enantiomers, they exhibit distinct physical properties such as different solubilities and melting points. These molecules occur when at least one, but not all, chiral centers undergo a configuration reversal. In biochemistry, understanding these spatial arrangements is vital for predicting how organic molecules interact with enzymatic active sites or receptor proteins. Rationale: A. Diastereomers are defined by having at least two chiral centers where the spatial configuration differs at one or more positions, but specifically not at all positions. If all centers were reversed, the molecules would be enantiomers. This partial variation creates unique molecular geometries and physical characteristics. Because they are not mirror images, they do not share the same internal energy or spatial relationships between non-bonded atoms. B. Non-superimposable mirror images describe enantiomers, not diastereomers. Enantiomers have identical physical properties in an achiral environment but rotate plane-polarized light in opposite directions. Diastereomers are not mirror images of one another because their stereochemical configurations do not match perfectly across all centers. This distinction is fundamental in organic chemistry for separating mixtures of isomers through fractional crystallization. C. Molecules that differ in configuration at only one asymmetric center among several are a specific sub-type of diastereomers known as epimers. While all epimers are diastereomers, not all diastereomers are restricted to a single center of variation. This choice is too narrow to define the entire class of diastereoisomeric compounds. True diastereomers can vary at multiple asymmetric carbons simultaneously without becoming full mirror reflections. D. Differing only at the penultimate carbon is a characteristic used to distinguish between D and L isomers in carbohydrate chemistry. This specific structural variation determines the optical series of a sugar but does not encompass the broad definition of diastereomers. Diastereomeric relationships can occur at any chiral center within a molecule, not just the distal carbon relative to the functional group.