How do the following processes affect the content of carbon dioxide in the air

How do the following processes affect the content of carbon dioxide in the air:
a) combustion of carbon-containing compounds,
b) the process of photosynthesis,
c) volcanic eruptions?
How can you slow down the rise in atmospheric carbon dioxide?

a) increases the level of carbon dioxide in the air b) lowers the level of carbon dioxide in the air c) increases the level of carbon dioxide in the air.
To slow down the growth of carbon dioxide, it is necessary to reduce deforestation and plant new trees in places of past deforestation; reduce the extraction and processing of fossil fuels; control carbon dioxide emissions in industry, for example by channeling carbon dioxide to synthesize methanol.