Which of the following describes a stereoisomer?

A stereoisomer is characterized by having atoms bonded in the same sequence, but arranged differently in three-dimensional space. This spatial arrangement leads to distinct physical and chemical properties, even though the connectivity of the atoms remains unchanged. The nuances of three-dimensional positioning are crucial for understanding stereoisomers, as they can exhibit isomerism in forms such as geometric (cis/trans) and optical (enantiomers) isomers.

The other descriptions presented do not align with the definition of stereoisomers. Specifically, variations in bonding sequence do not indicate stereoisomerism, but rather structural isomerism. Additionally, having entirely different molecular formulas implies that the compounds are completely different entities and not merely isomers. Lastly, isomers that can be easily superimposed are referred to as identical rather than stereoisomers, as true stereoisomers cannot be superimposed due to their distinct spatial arrangements.