#### Answer

D. After 8 seconds, Sam reached the mall door. We know this because of the x-intercept represented on the graph.

#### Work Step by Step

Step 1: Identify your x-intercept. The x-intercept is the point where the line touches or passes through the x-axis. So in this case, it touches at the (x,y) coordinate (8,0).
Step 2: Interpret your x-intercept. The x-axis is labeled time in seconds and the y-axis is labeled distance in feet from the mall door. Since the line touches at (8,0), this means that it took 8 seconds for the distance from the mall door to be 0 feet (meaning he was at the door).
Step 3: Find your answer. After 8 s, Sam reached the mall door.