Some astrobiologists have proposed that brine—water with a concentration of dissolved solids of more than 3.5%—may present conditions conducive to the evolution of life on extraterrestrial bodies. Unfortunately, remote observation is not sensitive enough to provide much information about the composition or even existence of brines on such bodies. Although studying meteorites found on Earth to infer information about brines from mineral deposits left behind when water evaporates is possible in principle, interactions with Earth’s atmosphere have likely altered or eliminated most of those deposits.
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Verbal·Craft and Structure·Text Structure and Purpose
mediumWhich choice best describes the overall structure of the text?
A
It describes a proposal about extraterrestrial brines that some astrobiologists have advanced, then presents evidence calling that proposal into question.
B
It discusses the difficulty of studying extraterrestrial brines directly, then suggests studying them via mineral deposits on meteorites.
C
It explains why extraterrestrial brines are of interest to astrobiologists, then discusses why such brines are likely rare.
D
It suggests the potential utility of studying extraterrestrial brines, then presents reasons why doing so is challenging.