Justin and Kira use functions to model the heights, in centimeters, of two sunflower plants x weeks after transplanting them to the school garden. Function j models the height of Justin’s plant: j(x) = 18 + 6x. Function k models the height of Kira’s plant: k(x) = 12 + 4x. Which function correctly represents how much taller Justin’s plant is than Kira’s plant, x weeks after they were transplanted to the school garden? A. (j − k)(x) = 30 + 10x B. (j − k)(x) = 6 + 10x C. (j − k)(x) = 6 + 2x D. (j − k)(x) = 30 + 2x