Explanation
Correct answer: A.
Choice A is the best answer because it most accurately states the main idea of the text. According to the text, artificial leaves are a renewable energy technology that’s in development and generating interest. The text goes on to state that artificial-leaf technology "is not yet commercially viable as a large-scale energy source" and that scientists from several fields are doing additional research to refine the technology. Thus, the main idea is that continued research and development in artificial-leaf technology is needed before the devices can be widely used as an energy source.
Why the other choices are wrong
Choice B
Choice B is incorrect. While the text does state that scientists from many fields are researching artificial leaves, they’re doing so to address the fact that the leaves are not yet commercially viable, rather than in response to an increase in commercial use.
Choice C
Choice C is incorrect. Although the text does explain that artificial leaves help split water molecules into oxygen and hydrogen gas using catalysts, it doesn’t argue that this process is more efficient than photosynthesis. This is merely a detail of the text and not the main idea, which is about the additional research needed to improve the cost and efficiency of these artificial leaves.
Choice D
Choice D is incorrect. Although the text indicates that artificial leaves mimic photosynthesis in plants, this is an incidental detail in support of the main idea that additional research is needed to make artificial leaves commercially viable.