Lichens, represented by this symbiotic relationship, are responsible for or the establishment of a new site for plant growth.
A. primary succession
B. secondary succession
C. trophic metamorphosis
D. ecological infiltration

A. primary succession

Explanation:

Lichens refers to a symbiotic relationship that occurs between two organisms. One popular example of this is the relationship between the fungus and the algae.

"Primary succession" typically starts in a barren area, such as a "bare rock." This area is considered a lifeless habitat. Since the "lichens" (a composite organism) are the ones which create an environment in the lifeless habitat, they are then responsible for the interaction that is initiated in the area. This interaction establishes the site for plant growth. Thus, it makes the lichens responsible for the primary succession.

So, this explains the answer.