To get appropriate bromoalkane an alkyne that were involved in the synthesis, we have to cleave the molecule and we know that sodium amide is involved, so the synthesis of 3-octyne using the alkyne and bromoalkane was $\mathrm{S}_{\mathrm{N}}2$ reaction. And as the sodium amide is involved, the alkyne involved must be terminal then only it could abstract the acidic hydrogen 3-octyne is a molecule that will have eight carbon atoms in their parent chain since the prefix-oct represents 8 and as in the name it is given that 3 octyne, ' 3 ' represents the position of triple bond. Thus suffix-one represents triple bond.

So, in the molecule triple bond will be at the third carbon. Structure of 3-octyne :

Now, cleave the molecule between $\mathrm{C}_2-\mathrm{C}_3$ or $\mathrm{C}_4$ - $C_5$.

Now, see the products formed if cleavage takes place between C₂-C₃, the reactants will be

If cleavage takes place between C₄-C₅, the reactants will be :

Then correct option is D.