সঠিক উত্তর হচ্ছে: Aluminium
ব্যাখ্যা:
Aluminum is the most abundant metal in the earth's crust, but it is never found free in nature. All of the earth's aluminum has combined with other elements to form compounds. Two of the most common compounds are alum, such as potassium aluminum sulfate (KAl(SO4)2.