The scatterplot below shows the amount of electric energy generated, in millions of megawatt-hours, by nuclear sources over a 10-year period.
The x-axis represents time (in years), and the y-axis represents energy (in million megawatt-hours)

Which of the following statements is true about the equation that best models the data in the scatterplot?
The value of is positive.
The value of is negative.
The value of is negative.
The value of is negative.