Which of the following configuration represents a therosteroisomer?

Options

A.
B.
C.
D.

Answer

B

Explanation

Molecules with two different chiral centres, not necessarily on adjacent carbon atoms, are frequenctly designated by the prefix threo-or erythro-provided both chiral carbons have at least two identical ligands. When two identical ligands (in this case two `H's`) are on the same side of the vertical bonds (as in `1,3` and `4)`, the molecule is called erythro (related to the sugar erythrose). WHen they are on opposite sides (as in `2`), the molecule is called threo (related to the sugar threose).