This is referred to the hydrogenation of alkynes.Hydrogenation of alkynes is a reaction that replaces one or more of an alkyne's pi bonds with hydrogen atoms. This process is a step-by-step reaction that typically converts a triple bond into a double bond, and then a double bond into a single bond.

This is applicable to option D because, you'll be needing 4 atoms of Hydrogen as shown in the question, to break the tripple bond, and convert first to double bond, and then to a single bond.