The #"optically inactive"# compound in those listed is #"2-chloropropane"#, which does not contain any chiral centres. The other molecules all possess a carbon(s) with 4 different substituents that can potentially generate 2 chiral centres.
For #H_3C-CHClCH_2CH_3#, #stackrel(2)C# is a potential chiral centre, that COULD allow separation of different enantiomers. And note that a chiral resolution of such a simple compound would be a big deal. On the other hand, we derive glucose and lactic acid from natural sources, which does all the tedious and time-costly resolution for us.