A student adds an excess of zinc to dilute hydrochloric acid at $25\,^{\circ}\text{C}$. The hydrogen gas formed is collected and its volume is measured at room temperature and pressure. The outcome is drawn on the graph and labelled curve X. The investigation is then carried out again at $50\,^{\circ}\text{C}$, while every other condition is kept unchanged. Which graph represents the results at $50\,^{\circ}\text{C}$?