Answer:
The correct answer is d all of the above
Step-by-step explanation:
There are many reasons behind increasing the concentration of atmospheric carbon dioxide such as
1 Burning of fossil fuels such as coal,petroleum increases the level of atmospheric carbon dioxide.
2 Increase in Argiculture also increases the level of green house gases such as CO2.
3 Clearing of lands for increasing population and agriculture by cutting down trees also adversely effect the normal 02:CO2 ratio in the atmosphere.