Which of the following isomers of 2,3‐dihydroxy‐4‐methoxy‐4‐oxobutanoic acid are identical? Which of the following are identical?


A and B are identical
A and B are diastereomers
A and C are enantiomers
A and B are enantiomers


What I know is that when we rotate a Fisher projection by 180°, then we get identical compounds (I might be wrong). But how to tell if the compounds are enantiomers of each other or not?
For that how to get the same group, i.e. $\ce{-COOH}$ in this case at the top to compare the compounds?
Also, is there any trick to tell that if they are diastereomers, enantiomers or identical by the hydroxyl group positions in Fisher projections?
On rotating the compound B by 180°, we get the two -OH groups on the left side and the two H atoms on the right. In other words, B would then be an enantiomer of A.

Note: on rotating a Fischer projection by 180°, the compound remains the same; it's just that all the atoms have to be rotated, i.e. the atoms on C3 in this case would go to C2 and vice versa.