Most ecosystems on Earth rely on as their source of energy. A. Chemical Energy B. the Sun
C. Hydrothermal Energy
be more faster i'm in a test

the answer is d (apex) good luck : ))

substitution is the answer in this case

primary succession occurs in essentially lifeless areas regions in which the soil is incapable of sustaining life as a result of such factors as lava flows, newly formed sand dunes, or rocks left from a retreating glacier. secondary succession occurs