Answer
The following transformation can be obtained with hydroboration of alkene.
Work Step by Step
Since the OH is attached to the least substituted carbon, this reaction takes place with hydroboration, instead of oxymercuration-demercuration. Borane adds to the double bond in a single step. Boron adds to the less hindered, less substituted carbon, and hydrogen adds to the more substituted carbon. And then $BH_2$ gets replaced by OH. There will be two products because borane can attack from either top or bottom.
