Identify the reactants

The reagent $CH_3MgX$ is a Grignard reagent. It behaves as a strong base as well as a nucleophile.

The other reactant is propyne: $CH_3C \equiv C-H$

This is a terminal alkyne, and terminal alkynes contain an acidic hydrogen.

Key concept: Grignard reagent + acidic hydrogen

Grignard reagents react with compounds containing acidic hydrogen atoms.

General reaction: $RMgX + R'-H \rightarrow RH + R'MgX$

Here:

• $R = CH_3-$
• $R'-H = CH_3C \equiv C-H$

So the methyl group abstracts the acidic hydrogen from the terminal alkyne.

Write the reaction

$CH_3MgX + CH_3C \equiv C-H \rightarrow CH_4 + CH_3C \equiv C-MgX$

Thus, the organic product formed from the Grignard reagent is methane.

Check the options

• A: $CH_3-CH=CH_2$ → not formed
• B: $CH_3C \equiv C-CH_3$ → not formed directly here
• D: $CH_4$ → formed

Final answer

The product is: $\boxed{CH_4}$

Hence, Option D is correct.