The correct IUPAC name is 4 – hydroxypentan – 2 – one.
The parent compound contains 5 carbon atoms. Hence, it is a derivative of pentane. The carbonyl group is present on second carbon atom. Hence, it is named pentan – 2 – one. The last alphabate 'e' of pentane is replaced with word – 2 – one. A hydroxyl group is present as a substituent on fourth carbon atom and is named as prefix.