The graph shows the volume of a gaseous product formed during two trials of a reaction. A different concentration of reactant was used during each trial, whereas the other factors were kept constant.

Which of the following statements explains which trial has a *lower* concentration of the reactant? (5 points)

Trial 1, because the average rate of the reaction is lower.
Trial 1, because this reaction lasted for a longer duration than Trial 2.
Trial 2, because this reaction was initially fast and later slowed down.
Trial 2, because the volume of product formed per unit time was higher.