Answer is: the number of ions produced in the dissociation of aluminium fluoride is 4.
Chemical dissociation of aluminium fluoride in water:
AlF₃(aq) → Al³⁺(aq) + 3F⁻(aq).
There are four ions, one aluminium cation and three fluoride anions.
Aluminium has oxidation +3, because it lost three electrons, to have electron configuration as noble gas neon and fluorine has oxidation -1, because it gain one electron to have electron configuration as noble gas neon.