原题
Silica cements associated with casts of soft-bodied marine organisms from the Ediacaran period (circa 538–635 million years ago) are plausibly attributable to one of two phenomena: rapid postmortem preservation of the organisms via precipitation of cements from silica-rich oceans or cement precipitation via high-pressure reactions long after the organisms were preserved by some other means. Recognizing that such reactions generally result in cements with germanium/silicon (Ge/Si) ratios lower than those of silica grains recovered from the same portion of sandstone, Lidya Tarhan et al. investigated silica cements and grains associated with Ediacaran soft-bodied casts at a site in South Australia.
Based on the information in the text and the graph, Tarhan et al. could most reasonably draw which conclusion?
AThe total number of cement samples is much lower than the total number of grains precipitated via high-pressure reactions, which suggests that rapid precipitation from silica-rich oceans could account for the preservation of the site’s organisms.
BThe distribution of Ge/Si ratios indicates that a portion of the cements could have precipitated via high-pressure reactions, which suggests that organisms at the site were less likely to have been preserved via rapid precipitation from a silica-rich ocean than Tarhan et al. hypothesized.
CThe range of Ge/Si ratios is larger for the cements than for the grains, which suggests that the cements are likely the result of high-pressure reactions that occurred long after the organisms were preserved by some other means than precipitation from a silica-rich ocean.
DThe distribution of Ge/Si ratios of the cements and grains is largely inconsistent with the cements having precipitated via high-pressure reactions, which implicitly lends support to the idea that the organisms at the site were quickly preserved by cement precipitation from a silica-rich ocean.
正确答案：D
解题思路
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