Answer: Pareto Chart
Step-by-step explanation:
A Pareto Chart is a type of chart that mixes both the line and bar graphs.
It works by putting the Frequency of the complaint categories on the vertical axis and the category on the horizontal axis.
The frequency bars are arranged from the most frequent to the least frequent and then there is a line that shows the cumulative frequencies of the complaint categories.
The benefit of this graph is that one can see the most frequent complaint as soon as they look at the graph which is why it is most useful to this question.
I have attached an example to better explain.