The quadratic function d = –2x2 + 15 models a skateboarder’s distance, in feet, from the bottom of a hill x seconds after the skateboarder starts moving down the hill. After how many seconds is the skateboarder 8 ft from the bottom of the hill? A. 0.9 s
B. 1.9 s
C. 3.4 s
D. 3.9 s