(2) cadmium in the order of activity of the metal table in front of hydrogen, can be reacted with hydrochloric acid to generate cadmium chloride and hydrogen, the equation is: Cd + 2HCl ═CdCl2 + H2 ↑, the reaction is generated by a compound and a single substance to generate another compound and a single substance, belong to the substitution reaction;

() 3) to reduce cadmium pollution, you can reduce the intake of food diversification;

The answers are: (1) D; (2) Cd + 2HCl ═ CdCl2 + H2 ↑, a replacement reaction; (3) the food as diverse as possible, through the dietary diversification to reduce the possible presence of pollutants in a particular food.