Which of the following gives white precipitate, with ammoniacal silver nitrate solution ?

Terminal alkynes containing an acidic acetylenic hydrogen react with Tollens' reagent (ammoniacal silver nitrate solution) to form insoluble metal acetylides. Acetylene (${\text{C}}_2{\text{H}}_2$) forms a characteristic white precipitate of silver acetylide (${\text{Ag}}_2{\text{C}}_2$):
$$\text{HC}\equiv \text{CH}+2[\text{Ag}({\text{NH}}_3{)}_2{]}^{+}+2{\text{OH}}^{-}\to \text{Ag}-\text{C}\equiv \text{C}-\text{Ag}\downarrow (\text{white})+4{\text{NH}}_3+2{\text{H}}_2\text{O}$$