What type of plot is most suitable for examining the percentage of students earning various grades?

To examine the percentage of students earning various grades, a bar chart is the most suitable type of plot. A bar chart effectively represents categorical data, where each category (in this case, the different grades such as A, B, C, etc.) is displayed with bars whose heights correspond to the percentage of students achieving each grade. This allows for easy comparison between the different categories.

A time plot is inappropriate here because it is specifically designed for displaying data points in time order, which is not relevant when analyzing grades that are categories rather than being measured over time.

Other graphical representations, like a line graph, typically connect individual data points, which is more useful for showing trends over continuous data rather than categorical comparisons. Similarly, a histogram is suited for numerical data divided into intervals and is not the ideal choice for categorical data like grades, as it focuses on the distribution of numerical values rather than percentages of distinct categories. Therefore, the bar chart is the correct answer for this scenario, facilitating a clear visual comparison between the grades.