The covalent character of a bond is determined by Fajan's rules. According to Fajan's rules, covalent character increases with:

• Small size of the cation
• Large size of the anion
• High charge on the cation
• Pseudo noble gas configuration of the cation

In the given options, the cation is Al³⁺, which is common to all halides. The anions are F^-, Cl^-, Br^-, and I^-. The size of the halide ion increases down the group:

F^- < Cl^- < Br^- < I^-

As the size of the anion increases, its polarizability increases, leading to a greater degree of covalent character in the bond. Therefore, AlI₃ will have the most covalent character.

• A) AlF₃: Fluoride ion (F^-) is the smallest halide ion, making AlF₃ the most ionic among the given options.
• B) AlCl₃: Chloride ion (Cl^-) is larger than F^- but smaller than Br^- and I^-. It has less covalent character than AlBr₃ and AlI₃.
• C) AlBr₃: Bromide ion (Br^-) is larger than Cl^- but smaller than I^-. It has less covalent character than AlI₃.
• D) AlI₃: Iodide ion (I^-) is the largest halide ion, making AlI₃ the most covalent among the given options due to the highest polarizability of I^-.

Correct Answer: (D)