The heat from the sun can't escape because of too much ______. [ ]

A. ozone

B. oxygen

C. carbon dioxide

D. radiation

当物体对水平面压力一定时，物体对水平面的压强随受力面积变化规律的图像如图所示，根据图像得出，压强随受力面积变化的表达式：                         。