ISSUE:

Mark the correct statement:
a) Diastereoisomers are stereoisomers that lack a plane of symmetry
b) Diastereoisomers are stereoisomers with different physical and chemical properties
c) Enantiomers are stereoisomers with the same physical and chemical properties.

Among the three options, I have ruled out c) because they do not have all the same properties, but between options a) and b) I do not know which one to take since b) is not entirely true since they are not all the properties so that I understand and a) I don't know if they lack a plane of symmetry or not

Hello, b) is correct.
A) is not correct since the enantiomers are also stereoisomers that lack a plane of symmetry. The set of spatial isomers of a molecule are called stereoisomers. Stereoisomers that are mirror images are enantiomers and the rest are diastereoisomers.

The only different physical property is the direction of rotation of the plane of polarized light.