Answer:
a. commensalism is the correct answer.
Explanation:
By growing on the trunk or branch of a tree, a lichen gains height and exposure to sunlight for photosynthesis. The tree is not harmed by the lichen but does not benefit either. The relationship between the lichen and the tree is commensalism.
Commensalism is a relationship between two organisms where one organism gets benefits from other organisms without causing any harm or any damage from the relation as it one side symbiotic relation.
In this, we can see lichen is getting benefits from the tree.
for example, lichen is getting following benefits from the tree such as ( a lichen gains height and exposure to sunlight for photosynthesis.) and they are causing any harm to tree neither any benefits so this is a one-side symbiotic relation and thus the relationship is an example of commensalism.
Roots and leaves
The major driving force of water uptake in a large tree is transpiration.Transpiration is the process by which plants absorb water through the roots and release it as water vapor through the pores in their leaves. Once this water evaporates, a negative water vapor pressure is created or develops in the surrounding cells of the leaf. when this happens, water is pulled into the leaf from the vascular system, the xylem, to replace the water that has been transpired from the leaf.This pulling of water, or tension, that occurs in the leaf, will extend through the rest of the xylem column of the tree right into the xylem of the roots as result of the cohesive force holding the water molecules along the sides of the xylem tubing.The xylem is a continuous water column extending from the roots to the leaves.<span>Finally, the negative water pressure that occurs even to the roots will result in an increase of water uptake from the soil.</span>
