Final answer:
The second step of primary succession typically involves lichens, which are pioneer species that grow on bare rock and help in soil formation. This sets the stage for other organisms to eventually colonize the area.
Step-by-step explanation:
Understanding Primary Succession
The second step of primary succession typically involves organisms that further break down raw substrates to enrich and form soil, which will allow more complex plants to grow.
Taking a closer look at the options given, the statement that best describes the second step of primary succession is: A. Lichens begin to grow and break down rock to form soil.
Lichens, being pioneer species, are crucial to this process.
They do not need soil to grow since they can sustain themselves on bare rocks through a symbiotic relationship between fungus and algae or cyanobacteria.
The lichen is capable of photosynthesis and weathering, the rock to create soil, which subsequently allows other organisms to colonize the area.
This soil formation is critical for the growth of subsequent plant life, such as mosses and grasses, which are also important in further soil development and nutrient addition but are seen in subsequent steps of succession.