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.

A graph is shown with two graph lines sloping upwards. The title on the x axis is Time and the title on the y axis is Amount of Product. The graph line with a steeper slope is labeled Trial 2 and the other is labeled Trial 1.

Which of the following statements explains which trial has a lower concentration of the reactant?

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.