In experiment 1 and experiment 3, both iron and zinc can react with acid to produce bubbles. The stronger the activity, the more intense the reaction. The metal activity of zinc is stronger than that of iron, and the answer C is correct. In experiment 2, putting copper into silver nitrate solution will replace silver, and it is concluded that copper is more active than silver, and the answer D is correct; The experiment shows that zinc is more active than iron and copper is more active than silver, but there is no experiment in which iron is more active than copper, so the answer A is correct. B Answer: By adding an experimental comparison of the activity of copper and zinc, it can be concluded that the activity of zinc is stronger than that of copper, but there is still no experiment that the activity of iron is stronger than that of copper. The answer is incorrect.

So choose B.