Ans. is 'a' i.e., It chelates with metal ions of the enzyme o EDTA is a chelating agent and it has already been explained that chelating agent has legands (reactive groups) for metal binding. o These ligands of chelating agent bind to metal ions and cause chelation. o EDTA binds to zinc ion of carbonic anhydrase and this results in formation of ternary complex involving the enzyme, chelating agent and metal ions. The formation of ternary complex results in inactivation of enzyme.