Final answer:
The activity that directly contributes to increased atmospheric carbon is the burning of fossil fuels. While other options like photosynthesis and fossilization reduce or have neutral effects on carbon levels, fossil fuel combustion releases significant amounts of CO2 into the atmosphere.
Step-by-step explanation:
Activities Increasing Atmospheric Carbon
The activity that increases the amount of carbon in the atmosphere from the provided options is b) the Burning of fossil fuels. Burning fossil fuels such as coal, oil, and natural gas releases significant amounts of carbon dioxide (CO2), a greenhouse gas, into the atmosphere. This contributes to global warming as CO2 traps heat within the Earth's atmosphere. In contrast, photosynthesis reduces atmospheric CO2 as plants convert carbon dioxide into glucose, a process that temporarily stores carbon. Fossilization locks carbon away in the Earth for long periods, while animals eating plants does not add additional carbon to the atmosphere as it is part of a natural cycle.
In terms of human actions that influence the carbon cycle and can potentially mitigate the impact of global warming, options such as A) Planting more trees, B) Burning less fossil fuels, and managing the number of heterotrophs and autotrophs can help reduce the atmospheric carbon levels. Moreover, human activities like deforestation and animal husbandry practices give rise to higher levels of CO2 and methane, influencing the greenhouse effect and biogeochemical cycles.