Carbon 4

Carbon 5

Carbon 1

Carbon 2

Carbon 3

One of a pair of stereoisomers, which differ in configuration at only one stereogenic center

Two or more stereoisomers of a compound which have different configurations at one or more (but not all) of the equivalent stereocenters and are not mirror images of each other

Stereoisomers that are not superimposable mirror images

There are no such things as epimers.

stereoisomers

constitutional isomers

conformers

identical

None of these