1. The problem asks: In Scatter Plot C, as the altitude increases, what happens to the atmospheric pressure in millibars (mb)? 2. From the description, Scatter Plot C shows a graph of points decreasing in a nonlinear curve. 3. This means as altitude (x-axis) increases, atmospheric pressure (y-axis) decreases, but not in a straight line. 4. Therefore, the atmospheric pressure decreases nonlinearly as altitude increases. Final answer: Atmospheric pressure decreases as altitude increases in Scatter Plot C.