Aluminum sulfate is widely used in water treatment facilities as a coagulant to clump microscopic impurities together for easier filtration. Based on the stable ions formed by its constituent elements and polyatomic groups, what is the correct chemical formula of aluminum sulfate?
Al3(SO4)2\text{Al}_3(\text{SO}_4)_2Al3(SO4)2
Al2(SO4)3\text{Al}_2(\text{SO}_4)_3Al2(SO4)3
AlSO4\text{AlSO}_4AlSO4
Al(SO4)2\text{Al}(\text{SO}_4)_2Al(SO4)2