Explanation

Magnesium is above hydrogen in the reactivity series, so it displaces hydrogen from dilute hydrochloric acid: Mg + 2HCl -> MgCl2 + H2. Copper with dilute nitric acid produces nitrogen oxides (NO/NO2) because nitric acid is an oxidising acid, not hydrogen gas. Calcium carbonate with hydrochloric acid gives carbon dioxide, and zinc with nitric acid also yields oxides of nitrogen rather than hydrogen. Therefore only magnesium with hydrochloric acid produces hydrogen.