I am pretty for sure the answer is roots.
Answer:
Hello. You did not enter the answer options, but the factor that most directly influences a measurable result in an experiment is the manipulation of the variables.
Explanation:
In an experiment, the manipulation of variables becomes highly important so that it is possible to measure, that is, evaluate the result. This is because it is the variables that express values that represent the characteristics that are being analyzed and studied within the experiment. Therefore, the manipulation between them must be done in a very rational and balanced way so as not to modify the values shown by them, changing the data and generating false or immeasurable data.
The region that would be eroded the most would be those at the slopes of the mountain. When heavy rainfall comes, the soil in these regions gets soften thus being forced down forming a run-off due to the force of gravity. These eroded soil would eventually continue to the valleys thus causing landslides.