We have to identify the line that best fit the points in the scatter plot.
In this case, we are not working with the equations of the line.
We have to look at the usual properties of the line of best fit.
It is expected to half of the points above and half of the points below.
It also has to follow the trend of the points. This is related to the previous point.
We can check each of the graphs:
First line:
We can see that this line seems to have the rigth slope, but is much closer to the points that have greater weight per book than the the ones that do not.
It is not the best line fit.
Second line:
This case is similar to the previous one, but in this case is closer to the bottom points with no reason. It also looks like the slope is smaller than what it should be, but it can not be determined precisely.
This is not the line of best fit.
Third line:
This line seems to represent the correct trend and is equally distanced from most of the points, grouping them in half above and below the line.
This is a good candidate for best fit line.
Fourth line:
This line is only representative of the trend of the leftmost points. It does not include the right points, so the actual trend is not represented by this line.
This is not the line of best fit.
Answer:
The graph that shows the line of best fit is