Which of the following is most basic in aqeous Solution?

• The basicity of amines increases when there are more electron-donating groups and decreases when electron withdrawing groups are attached to it. 
• And aryl substituted amines are less basic than alkyl substituted because the electrons in aryl amines participate in resonance thus the electron density is distributed all over the aromatic ring. 

Hence, from the given compounds, Pyrrolidine C₄H₉N is the most basic in aq. Solution as it is a secondary cyclic amine with no -bonds available for conjugation.