Green house gases are responsible for keeping the earths temperature warm. Increase in the concentrations of greenhouse gases tends to have direct effect on the increase in the temperature of earth. Such gases include carbon dioxide, methane, etc. So if carbon dioxide levels increase, then the overall temperature of the earth also increases. Hence, option (a) is correct.
For the better maintenance of the ecosystem, there are various mechanisms that act aptly. Oceans act as sinks to absorb the excess amount of carbon dioxide that is present in the atmosphere. But this occurs at a very slow rate. Hence, the level of carbon dioxide cannot decline soon. Hence, option (b) is incorrect.
It’s not the warmer temperature that increases the carbon dioxide concentration. Instead, it is the Carbon dioxide concentration that is directly proportional to the rise in temperature. Hence, option (c) is incorrect.
The rise in the concentration of carbon dioxide results in the increase of temperature of the earth. Therefore, the components are not indirectly but are directly proportional. Hence, option (d) is incorrect.
Decrease in the temperature elsewhere does not compensate for the rise in the level of carbon dioxide in some other place. Neither will this decrease in temperature elsewhere result in increasing the concentration of CO2 at some other place. Hence, option (e) is incorrect.
Therefore, based on the graph given in the question, the most likely explanation is (a) carbon dioxide and temperature will increase proportionally.