Answer:
0 meters
Explanation:
When we talk about displacement, think that the think of it as the measure of the distance between the starting point of the object, from its end point.
Since we are talking about a lap around a track, it would mean that the starting point is also the end point. So if you started and end at the same point, the distance between it would be 0.
As for this problem, the most probable answer and the most likely answer for this one would be D. the effect of pesticides on organisms in the environment.
A toxicologist would only study about chemicals and their effect on organisms in the environment. Pesticides are chemicals made to combat organisms that aren't wanted particular parts of the environment such as crops and rice field. These pesticides don't just affect those organisms that are targeted, but even the users and other organisms that may have come in contact with pesticides.
I think the answer is liver and hepatic portal vein
Hope this helps