Reaction Rates Practice Test

The concentration of reactant $\text{H}(aq)$ is plotted versus time for a reaction. At which time is the instantaneous rate of disappearance of $\text{H}$ greatest (i.e., where the magnitude of the slope is largest)?

A student measures the concentration of reactant $\text{D}(aq)$ during a reaction. Which time interval shows the greatest average rate of disappearance of $\text{D}$?