An increase in human-made carbon dioxide in the atmosphere could initiate a chain reaction between plants and microorganisms that would unsettle one of the largest carbon reservoirs on the planet - soil. In a study, it was found that the soil, which contains twice the amount of carbon present in all plants and Earth’s atmosphere combined, could become increasingly volatile as people add more carbon dioxide to the atmosphere. This is largely because of increased plant growth. Although a greenhouse gas and a pollutant, carbon dioxide also supports plant growth. As trees and other vegetation flourish in a carbon dioxide-rich future, their roots could stimulate microbial activity in soil that may in turn accelerate the decomposition of soil carbon and its release into the atmosphere as carbon dioxide.

Which among the following is the most logical corollary to the above passage ?

The correct option is: "Increasing green cover could trigger the release of carbon trapped in soil."

Step-by-step Explanation:

1. Understanding the Passage's Premise: The passage describes a feedback loop initiated by increased carbon dioxide in the atmosphere. Carbon dioxide, while a pollutant, acts as a fertilizer that supports plant growth, causing trees and vegetation to flourish. This flourishing of vegetation is represented as "increasing green cover."

2. Analyzing the Chain Reaction: The text explains that as vegetation grows more abundantly, their roots stimulate microbial activity in the soil. These microorganisms then accelerate the decomposition of soil carbon, releasing it into the atmosphere as carbon dioxide.

3. Deriving the Corollary: By linking these points together: increased carbon dioxide leads to flourishing vegetation (increased green cover), which stimulates soil microbes, which in turn decomposes and releases the carbon trapped in the soil. Therefore, a logical corollary is that increasing green cover can act as the trigger for releasing soil-bound carbon.

4. Evaluating Other Options:
- "Carbon dioxide is essential for the survival of microorganisms and plants.": The passage states that carbon dioxide supports plant growth, but it does not claim it is essential for the survival of all microorganisms.
- "Humans are solely responsible for the release of carbon dioxide into the atmosphere.": The passage mentions human-made carbon dioxide as a starting trigger, but it does not state that humans are the only source of atmospheric carbon dioxide.
- "Microorganisms and soil carbon are mainly responsible for the increased plant growth.": This reverses the cause-and-effect relationship. According to the passage, plant growth is what stimulates the microorganisms, not the other way around.