Guanidine is a stronger base than the typical amine. The increased basicity can be explained by drawing the resonance structures of the protonated guanidine. The protonated guanidine (A) has been drawn for you. Draw major resonance structures, one each in boxes B and C, and one minor resonance structure in Box D. Be sure to include the formal charge, lone pairs, and hydrogens on nitrogen for structures B, C, and D.