Answer:
"The car travels different distances per unit of time because the portion shows a non-linear, increasing function." which is the third option listed.
Explanation:
Section K of the journey is NOT linear, but represents a non-constant increase in distance covered as a function of time (thus not same distance per unit time that a straight line would show). It shows that as time goes by, larger and larger distances are covered.
So the most accurate option among the listed possible answers is the one that reads: "The car travels different distances per unit of time because the portion shows a non-linear, increasing function."