What is the primary difference between stereoisomers and enantiomers?

• A. Stereoisomers are always chiral, while enantiomers are always achiral.
• B. Stereoisomers have different atomic compositions, while enantiomers have the same atomic composition.
• C. Stereoisomers differ in their 3D spatial arrangement, while enantiomers are non-superimposable mirror images.
• D. Stereoisomers can be converted into enantiomers by breaking and reforming bonds.

Answer: (C)