Priority order at `C-2` :
Written as
First assign `R//S` at `C-2`. Here, the lowest ligand is in the plane (i.e., on the dotted line). Priority sequence is anticlockwise, hence the configuration at `C-2` is `S`.
Priority order at `C-3: -OH gt -CHOHCHOgt -CH_(2)OHgtH`
Here, `H` is not on the dotted line, so make one interchange of `H` and `-OH` so that `-OH` is projected away from the observer.
So, the configuration is `(2S, 3R)`.
