Among the given salts FeCl3​ is acidic in nature i.e., have acidic solution as it is the salt of weak base and strong acid.
Al(CN)3​ and Pb(CH3​COO)2​ are the salts of weak acid and weak base.
CH3​COOK is the salt of strong base and weak acid.
Hence, the solution of CH3​COOK will be most basic because of the following reaction.
CH3​COOK+H2​O⇌ (Weak acid) CH3​COOH​+ (Strong base) KOH​