SAT Two-variable data: models and scatterplots Question

As part of a study on sedimentary habitats, the water temperature was recorded at different depths below the surface of the water in the northern Alboran Sea. The data shown in the scatterplot give the recorded temperature, in degrees Celsius, for 7 depths, in meters, below the surface of the water. The scatterplot has 7 data points. The data points are in a linear pattern trending down from left to right. The data points have the following approximate coordinates: (15,22.30) (22,21.30) (35,16.20) (47,17.20) (51,16.20) (54,14.30) (70,13.30) Which of the following is closest to the slope of a line of best fit for the data shown?