Identify the amine having highest pK _ b value.

Step-by-step solution

The pK _ b value increases with decreasing base strength, so identifying the weakest base among the options determines the answer. Amine basicity depends on inductive effects, resonance, and solvation. Trimethylamine ( CH ₃)₃ N has electron-donating methyl groups but faces steric hindrance and reduced solvation. Benzylamine C ₆ H ₅ CH ₂ NH ₂ behaves as an aliphatic amine with attenuated electron withdrawal from the phenyl group. Aniline C ₆ H ₅ NH ₂ exhibits resonance delocalization of the nitrogen lone pair into t