Which property is true of diastereomers regarding their optical activity?

Diastereomers are a type of stereoisomer that are not mirror images of each other and typically have different physical properties, including optical activity. Optical activity refers to the ability of a substance to rotate plane-polarized light. Diastereomers can have different configurations at one or more stereocenters, leading them to interact differently with polarized light.

The correct choice indicates that diastereomers exhibit polarimetry differently. This means that each diastereomer will rotate polarized light to a different degree and possibly in different directions, depending on the specific three-dimensional arrangement of their atoms. This property allows for their distinction and can be used in analyses to separate and identify these compounds, as their distinct optical activities provide clear differences in their behavior under polarimetry.

In contrast, enantiomers, which are pairs of stereoisomers that are mirror images of each other, rotate light in equal magnitudes but in opposite directions. Thus, while enantiomers behave in a predictable manner concerning optical rotation, diastereomers do not share such symmetries, leading to their differing polarimetric behavior.