Option 1 states that iron is the reducing agent. A reducing agent is a substance that causes another substance to undergo reduction, which involves gaining electrons. In this reaction, iron is indeed the reducing agent as it loses electrons and is oxidized.

Option 2 mentions that the solution turns green in color after the reaction. This is correct as the reaction involves the formation of green iron(II) sulfate. The formation of this compound gives the solution its green color.

Option 3 states that copper is a more reactive metal than iron. However, this statement is incorrect. Copper is not more reactive than iron. In the reactivity series, iron is higher than copper. This means that iron is more likely to lose electrons and undergo oxidation than copper.

Option 4 states that the reaction is an example of a redox reaction. This statement is correct. A redox (reduction-oxidation) reaction involves a transfer of electrons between species. In this reaction, iron loses electrons (is oxidized) while copper gains electrons (is reduced), thereby fulfilling the criteria for a redox reaction.

In conclusion, option 3 is the correct answer as it incorrectly states that copper is more reactive than iron.