The graph below shows kate's distance from her home (y), in miles, after a certain amount of time (x), in minutes:

four students described kate's motion, as shown in the table below:

student
description
mary
she drives at a variable speed for 2 minutes, then drives at a constant speed for 6 minutes, and finally stops at the parking area for the next 8 minutes.
lucy
she drives at a variable speed for 2 minutes, then drives at a constant speed for 6 minutes, and finally stops at the parking area for the next 2 minutes.
tim
she drives at a variable speed for 2 minutes, then drives at a constant speed for 4 minutes, and finally stops at the parking area for the next 2 minutes.
pamela
she drives at a variable speed for 2 minutes, then drives at a constant speed for 4 minutes, and finally stops at the parking area for the next 8 minutes.

which student most accurately described lisa's motion?

mary
lucy
tim
pamela