The phrasing of this question is not ideal, but is appears that there are 3 multiple choice options:
a. change data
b. organize data
c. compare data
d. view trends in data
The correct answer in this scenario is that is is best to use a graph to represent data when one wants to: view trends in data (d.). Trends are most easily interpreted in visual format as graphs or charts as opposed to tabular form because patterns can be immediately observed. They are a powerful tool in science. A chart is in fact a graph so the question could be written better.