The scatterplot above shows the diameter x, in inches, and the age y, in years, of more than 40 trees in a certain park. Which of the following best describes the trend line of the scatterplot?

A) 2x+20
B) 5x+20
C) 10x+20
D) y=4x
E) y=12x

I got this one right, but it was really just a lucky guess. Scatterplots make no sense to me.