Calcium silicate (slag) formed in the slag formation zone is extraction of iron from haematite ore
I. does not dissolve in molten iron
II. being lighter floats on the moltern iron
III. Is used in cement industry
IV. prevents the re-oxidation of molten iron
A. 1, 2
B. 1, 3
C. 1, 4
D. `1, 2, 3, 4`
