What undefined terms is used to define a ray

Acompany is testing in comparing to lightbulb designs the box plot shows the number of hours that each lightbulb design last before burning out which statement is best supported by the information of the plot

What is the slope of the line that contains the points (4,8) and (9,8)? what type of line is it?

This question awards 100 ! i really don’t want to fail i will also mark you !