One way to refine iron from iron ore is to heat the ore with hydrogen gas at high temperatures. which change increases the amount of iron produced in the equation increase pressure add water to the system increase temperature reduce the amount of fe3o4

The correct option is INCREASE IN TEMPERATURE.
When iron ore is heated with hydrogen gas at high temperature, the element iron and water will be produced. One condition that this chemical reaction needs to occur is high temperature. The higher the temperature used, the higher the amount of iron that will be produced, this is because the presence of high temperature is the one driving the amount of iron produce. Thus, increase in temperature will leads to higher yield of iron.