We can use the vertical line test to check if each graph is a function. If the line passes through two points, it is not a function. If it only passes through one point then it is a function.Graph 1:It is a function because the line doesn't pass through more than one point. (yellow)Graph 2:It is not a function because the line does pass through more than one point. (orange)Graph 3:Horizontal lines are not functions. (orange)Graph 4:It is a function because the line doesn't pass through more than one point. (yellow)Best of Luck!