With a chemical formula of ${\mathrm{C}}_3{\mathrm{H}}_8$ , propane is a three-carbon alkane . At normal temperatures and pressures, it is a gas, but it can be compressed into a liquid that can be moved around.

Two isomeric monochloro derivatives of propane are1-chloro propane;  ${\mathrm{CH}}_3-{\mathrm{CH}}_2-{\mathrm{CH}}_2\left(\mathrm{Cl}\right)$  and 2-chloro propane; ${\mathrm{CH}}_3-\mathrm{CH}\left(\mathrm{Cl}\right)-{\mathrm{CH}}_3$

Hence, correct option is: (D) Propane