When is a chart legend used a. all the time b. whenever you are comparing data that is the same c. whenever you are comparing multiple sets of data d. only for hand-drawn charts

Chart legends are used whenever we are comparing multiple sets of data. A legend helps describe each part that make up a chart. It is most frequently situated on the right-hand side of the chart or graph and can occasionally be enclosed by a border and mostly used to compare data. Anytime data appears in a chart containing multiple data Series, it becomes easier to read if they are shown in a legend.

the answer is clip art