Question

1. how has human activities such as combustion of fossil fuel affect the carbon cycle?

o it has decrease atmospheric carbon
o it has increase atmospheric carbon

Explanation:

Human activities like burning fossil fuels (coal, oil, gas) release large amounts of carbon dioxide ($\ce{CO_2}$) into the atmosphere. The natural carbon cycle has processes that absorb and release carbon, but the combustion of fossil fuels adds more carbon to the atmosphere than natural processes can quickly remove, leading to an increase in atmospheric carbon. So the correct option is the one stating "It has increase atmospheric carbon".

Answer:

The correct option is: "It has increase atmospheric carbon" (assuming the option is labeled appropriately, e.g., if the second circle - based option is "It has increase atmospheric carbon", then the answer is that option. From the text, the two options are "It has decrease atmospheric carbon" and "It has increase atmospheric carbon", and the correct one is the latter as fossil fuel combustion adds $\ce{CO_2}$ to the atmosphere, increasing atmospheric carbon.)