The most common cause is the accuracy of the measurement instruments. And the observation of operator is also an important factor. That's why one measurement should do three times and use the average.
Hope this helps!
-Payshence xoxo
B is the correct answer because none of this that you put are testable.
You need to include a picture of the diagram and the problem in order to get an answer to your question
The source of inorganic fertilizer is from plant or animal based materials that are either a byproduct or end product of naturally occurring processes like leaves, and compost.
Lack of predators.
An abundance of Food.