The correct options are
A Reacting with non-metal
B Chrome plating
Methods which can be used to prevent the metal from rusting are:
In galvanizing, the metal is dipped in molten zinc which acts as a protective layer.
In chrome plating, a thin layer of chromium is electroplated on to the surface of the metal.
Reacting metal with a non metal results in the formation of an alloy which prevents the metal from rusting.
Crystallisation is not a method which prevents metal from rusting. It is a separation technique that is used to separate. a solid that has dissolved in a liquid and made a solution.