Find the four second mark on the X-axis of the graph. What comment BEST describes the two objects' motion from 0 to 4 seconds?
A) Both objects show constant acceleration.
B) Both show constant velocity but Accel 2 is about 4X faster than Accel 1.
C) Both have a constant rate of acceleration but Accel 2's rate is about 4X that of Accel 1.
D) Accel 1 has a constant rate of acceleration; Accel 2 accelerates at different rates during the trip.