Step 1: Reaction principle.
Carbylamine reaction (isocyanide test) occurs with primary amines.
Step 2: Application.
- Primary amine (CH\(_3\)NH\(_2\)) gives foul-smelling isocyanide.
- Secondary and tertiary amines (B, C, D) do not give the reaction.
Step 3: Conclusion.
Hence, the correct answer is
CH\(_3\)NH\(_2\).