All the salts given in the options are neutral because they are composed of cations and anions of strong bases and acids respectively. However, since the question asks for the salt that produces the lowest pH, we can consider the hydrolysis of the cations and anions of the salt. The cations of Group 1 and Group 2 metals and Li+ are neutral, and their hydrolysis is negligible. However, AlCl3 produces the highest number of H+ ions (protons) when dissolved in water because its cation, Al3+, undergoes hydrolysis to produce H+ ions. Thus, the solution with AlCl3 will have the lowest pH. Therefore, the correct answer is (d) AlCl3.