When an international team of scientists pumped a carbon dioxide and water mix into underground basalt rocks, basic chemistry took over. The acidic mixture dissolved rocks’ calcium and magnesium and formed limestone. Basically carbon dioxide is converted into stone, exclaimed the scientists.

Which one of the following statements best reflects the most logical, rational and practical suggestion implied by the passage?

The correct option is: "This can be used as one of the methods of carbon sequestration."

Step-by-Step Explanation:

1. Analyze the passage:
The passage describes a scientific process where a mixture of carbon dioxide (CO₂) and water is pumped into underground basalt rocks. This acidic mixture reacts with the calcium and magnesium in the rocks, turning the carbon dioxide into solid limestone. The scientists summarize this by stating that "carbon dioxide is converted into stone."

2. Understand Carbon Sequestration:
Carbon sequestration refers to the process of capturing and storing atmospheric carbon dioxide to mitigate global warming and climate change. By permanently turning gaseous carbon dioxide into solid stone (limestone) underground, this process prevents the gas from returning to the atmosphere.

3. Evaluate the options:
- Option 1 ("cheap and practical method to produce limestone at commercial level"): The passage mentions the formation of limestone, but it does not provide any information regarding the cost-effectiveness, commercial viability, or practical scalability of this method for building construction.
- Option 2 ("This can be used as one of the methods of carbon sequestration."): This directly aligns with the chemical process described, where carbon dioxide is locked away permanently in a solid mineral form (stone), preventing its release into the atmosphere.
- Option 3 ("Basalt rock can be made a good source of calcium and magnesium minerals"): The process actually dissolves the calcium and magnesium in the rock to form limestone, rather than extracting these minerals for other uses.
- Option 4 ("Good rock-dissolving acid can be produced by mixing carbon dioxide and water"): While the acidic mixture does dissolve rock, the primary significance of the experiment is the conversion of carbon dioxide into stone, not the production of acid for its own sake.

Therefore, the most logical, rational, and practical suggestion implied by the passage is that this process can serve as a viable method for carbon sequestration.