Answer:
The correct answer will be competition.
Step-by-step explanation:
Each forest is divided vertically into several layers forming a biologically complex living space due to the different height of the trees and the plants.
This vertical layering in the forest is known as "stratification" which is caused by the main factor of sunlight. Trees show this vertical layering in the forest in response to sunlight so that they can receive maximum sunlight from the sun to prepare the food for them.
This is a competitive type of interaction for survival with members of the same species or different species.
Thus, competition is the correct answer.