Correct Answer - A
Only option (a) , i.e., strength of Lewis acids decreases in the order : `BCl_(3) gt AlCl_(3) gt GaCl_(3)` is correct while all other options are incorrect as explained below :
Al does not show inert pair effect, `Tl^(3+)` has the highest oxidising power while ionization enthalpy of Tl is higher than that of Al.