Amongst the following, the strongest base in aqueous medium is

CH3NH2 NCCH2NH2 (CH3)2NH C6H5NHCH3

(CH3)2NH

2º Amines are more basic than 1º, i.e., (CH3)2NH is more basic then CH3NH2. Due to -I-effect of CN group, NCCH2NH2 is less basic than even CH3NH2. C6H5NHCH3 is less basic than both CH3NH2 and (CH3)2NH due to delocalization of lone pair of electrons on the N-atom into the benzene ring.