Answer:
a bar chart
Step-by-step explanation:
A bar chart is a graphical representation of representing data in rectangles form with length of the bar or height of the bar showing the values of the data. In representing the data, there should be two variables corresponding to which bars are represented. It is the easiest and the most convenient way to represent data in a graph.
In the context, the sales manager prepares a chart of the number of customers and the volumes of sales during the day by representing these values in the form of the graph known as bar graph.