The hydrocarbon which can react with sodium in liquid ammonia is:

Terminal alkynes (alkynes with a triple bond at the end of the chain) have acidic hydrogen atoms attached to the $sp$ -hybridized carbon. These hydrogens can be replaced by sodium metal or sodium amide (${\text{NaNH}}_2$) in liquid ammonia to form sodium acetylides.In the given options, only ${\text{CH}}_3{\text{CH}}_2\text{C}\equiv \text{CH}$ (But-1-yne) is a terminal alkyne.