Most carbon dioxide (CO2) emissions linger in the atmosphere, contributing to global warming. To address this, scientists have developed a method to inject captured CO2 into underground basalt rock. The CO2 reacts with the rock and turns into stone (mineralization). This solid mineral is stable and will not leak back into the atmosphere. With this promising method, greenhouse gases could be permanently locked away.
Which choice best states the function of the underlined portion of the text?
It clarifies the chemical process of turning gas into stone.
It describes the dangers of basalt rock.
It explains why the method was originally considered a failure.
It identifies the scientist who discovered the method.
Correct Answer: A
Choice A is the best answer. The text mentions "turning into stone." The underlined part (in parentheses usually, or explaining the reaction) clarifies that the CO2 reacts with rock to become solid.
Choice B is incorrect. It says the mineral is stable, not dangerous. Choice C is incorrect. It calls the method "promising," not a failure. Choice D is incorrect. No scientist is named.