Answer: B. sea level
The earth biosphere is a thin layer of the planet earth where life exists. This layer lies 10 km above the sea level. The biosphere is a region where living beings like plants, animals, microorganisms and others live and interact with the surrounding physical environment.
The temperature, pressure exerted by air and water and oxygen availability all can affect the earth's biosphere. But the earth biosphere is least affected by the earth biosphere because earth biosphere lies 10 km above the sea level.