It is crucial to study ocean microbes because a. they control the major biogeochemical cycles that keep earth’s biosphere in balance b. they are a significant source of greenhouse gases and pollution c. they are frequently used as food sources in developing nations d. they provide a significant alternative energy source used to replace coal and oil

a. they control the major biogeochemical cycles that keeps the Earth's biosphere in balance.

It is crucial to study ocean microbes because they control the major biogeochemical cycles that keeps the Earth's biosphere in balance. The dead aquatic plants and animals gets settled at the oceanic bed. The oceanic microbes conducts the process of decomposition over these organisms, so that energy from these organic matter gets circulated in the marine food chain. The organic matter produced after decomposition is buried beneath different sedimentary layers is a rich source of carbon. Some of these layers are superficial and they are carried away by high water currents to the middle and superficial layers of oceanic water body. Therefore, the carbon from oceanic bed is taken away to superficial water layer. This way carbon released out along with evaporated water to the atmosphere. Therefore, microbes control the major biogeochemical cycles that keeps the Earth's biosphere in balance.  

they dont have any evidence