Abar graph in which the bars are arranged in frequency order is
a. a. dotplot.
b. pie chart.
c. line chart.
d. pareto chart.

It is the Pareto Graph. It is a bar graph in which bars are arranged in frequency order. Pareto graph is the combination of bar and line graph that displays the data in a descending order.  It has an 80/20 rule.

Undefined

Step-by-step explanation:

☆ (x₁, y₁) is the first coordinate and (x₂, y₂) is the second coordinate.

Slope of the line

Thus, the slope of the line is undefined.

(Since 2 cannot be divided by zero)

Notice that the two coordinates have the same y- coordinate of -4. This means that the line is a vertical line. Vertical lines have undefined slopes.