Final answer:
Soil formation on volcanic rock through the presence of lichens and weathering represents the start of primary succession, where pioneer species such as lichens play a crucial role in developing the ecosystem.
Step-by-step explanation:
Understanding Primary Succession and Pioneer Species
Soil formation begins with the weathering down of volcanic rock into smaller pieces through the action of lichens and other factors, marking the start of primary succession. This process is critical in newly exposed or formed lands, such as areas affected by volcanic activity.
The first organisms to colonize these new environments are known as pioneer species, which include hardy plants, bacteria, and particularly lichens capable of living on bare rock without the need for soil. As these pioneer species live, grow, and eventually die, they contribute to the gradual buildup of organic material, resulting in the formation of soil. This enables other species that require more developed soil to move in, leading to a progression of the ecosystem until a stable climax community is established.
In the given question, soil formation via the breakdown of volcanic rock during the presence of lichens and weathering directly relates to the earliest stage of ecological development known as primary succession. Therefore, the correct answer to the question is B. primary succession.