Tracie rides the bus home from school each day. The graph represents her distance from home relative to the number of minutes since the bus left the school. A coordinate plane showing Driving Home. The x-axis shows Time in minutes and the y-axis shows Distance from Home in miles. The line starts at (0, 9) and passes through (2, 8), (4, 7), and ends at (10, 4).
What does the slope of the graph mean?

Tracie’s bus travels towards her home at an average speed of StartFraction one-half EndFraction mile per minute.
Tracie’s bus travels towards her home at an average speed of 2 miles per minute.
Tracie’s bus travels away from her home at an average speed of StartFraction one-half EndFraction mile per minute.
Tracie’s bus travels away from her home at an average speed of 2 miles per minute.