B. Hydrogen gas combining with oxygen gas to form water.
Answer - Immigration
Reasoning - With the a population of reproduction and stability you can also have added additional immigration of species which will boost the size of the population.
The Earth's system is divided in four subsystems: land (lithosphere), water (hydrosphere), air(atmosphere) and living things (biosphere).
Carbon is sixst most common chemical element on Earth.
<span>The most carbon on Earth is stored in a surprising place: the ocean.</span><span>This means that the most of carbon is stored in the lithospehere.
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Carbon is most abundant in the core and in the atmosphere.
A good reason for why tobacco smoke is considered a carcinogen is because it causes mutations leading to cancer.