What was the environmental factor MAINLY responsible for the changes which were seen in the graph in Figure 3?

my answer

Explanation:

the sun is rusing in noon and at it's very height, carbon-dioxide levels are LOW because the more sunlight plants get, THE MORE PLANTS CONVERT SUNLIGHT WITH CARBON DIOXIDE INTO OXYGEN AND REMOVE CARBON DIOXIDE FROM ATMOSPHERE

it seems that there aren't any factors that can really support it but i would say that the percent seems to lower because of the temp change

Explanation:

your answer should be c) enjoy!