The correct option is
A 2-chloro-2-methylpropane
The correct numbering of the parent chain is
Halogens are always used as substituent and is present at 2nd carbon. Also one methyl group is present as substituent at 2nd carbon. Since parent chain is of 3 carbon so word root is prop. the correct IUPAC name is 2-chloro-2-methylpropane.