Final answer:
Edward should create a bar chart to use vertical rectangles to compare iPod and iPad sales, as it is well-suited for displaying comparisons among discrete categories.
Step-by-step explanation:
Edward should create a bar chart if he wants to use vertical rectangles to compare iPod and iPad sales. Bar charts are appropriate for displaying comparisons among discrete categories or groups, such as sales figures for different products. In a bar chart, the length of each bar represents the value for each category—in this case, the number of iPods and iPads sold—making it easy to visually compare the differences between the two.
A pie chart would show the proportion of total sales that each product represents, which is not the type of comparison Edward is seeking. A line chart is more suited for displaying trends over time rather than direct comparisons. Meanwhile, a radar chart is less common and used for displaying multivariate data on a two-dimensional graph; it would not be as effective for the simple comparison that Edward is looking to make. Therefore, the correct answer is b) Bar chart.