What is the equation of the blue line?

On a architect's drawing of a house, 1 inche representa 1.5

The scatter plot graph shows the average annual income for a certain profession based on the number of years of experience which of the following is most likely to be the equation of the trend line for this set of data? a. i=5350e +37100 b. i=5350e-37100 c. i=5350e d. e=5350e+37100

[10 points, algebra 2]according to my answer key the restrictions are -1 and 4. but why not positive 1?