Using NASA’s powerful James Webb Space Telescope (JWST), Mercedes López-Morales and colleagues measured the
wavelengths of light traveling through the atmosphere of WASP-39b, an exoplanet, or planet outside our solar system.
Different molecules absorb different wavelengths of light, and the wavelength measurements showed the presence of
carbon dioxide (CO₂) in WASP-39b’s atmosphere. This ﬁnding not only offers the ﬁrst decisive evidence of CO₂ in the
atmosphere of an exoplanet but also illustrates the potential for future scientiﬁc breakthroughs held by the JWST.
It discusses a method used by some researchers, then states why an alternative method is superior to it.
It describes how researchers made a scientiﬁc discovery, then explains the importance of that discovery.
It outlines the steps taken in a scientiﬁc study, then presents a hypothesis based on that study.
It examines how a group of scientists reached a conclusion, then shows how other scientists have challenged that
Choice B is the best answer. The text begins by describing how the researchers used the JWST to detect CO₂ in WASP-39b’s
atmosphere. Then the text discusses the signiﬁcance of this ﬁnding, both as the ﬁrst evidence of CO₂ in an exoplanet’s
atmosphere and as an illustration of the JWST’s potential for making new discoveries in general.
Choice A is incorrect. The text doesn’t compare two different methods, but rather focuses on one study that used the JWST.
Choice C is incorrect. The text doesn’t present a hypothesis, but rather reports on the ﬁndings of a study. Choice D is
incorrect. The text doesn’t mention any scientists challenging the conclusion reached by López-Morales and colleagues.