Xiaoling summed up some of her chemistry knowledge as follows. Among them, the wrong group is () A, the nature and use of substances, and B, safety.

A, the chemical nature of nitrogen is not active, and it is not easy to react with other substances under normal circumstances, so it can be used as a food protection gas; Ethanol is flammable and can be used as fuel; Carbon monoxide is reducible and can be used to smelt metals.

B, fake wine often contains methanol, which is harmful to human body; The main component of gas is methane, which is flammable; Fake salt is poisoned because sodium nitrite in fake salt is harmful to human body.

C, iron deficiency in human body is easy to cause anemia; Calcium deficiency in human body is prone to rickets or osteoporosis; The human body is prone to goiter due to iodine deficiency.

D, oil is easily soluble in gasoline; Hard water and soft water can be distinguished by soapy water; Increasing the contact area between combustible materials and oxygen can promote combustion.

So choose B.