Nhận biết (M1)

The ratio of methane to other atmospheric constituents—represented by a measure called the methane mole fraction—influences a variety of meteorological phenomena, notably precipitation and humidity. For Titan, Saturn’s largest moon, the observational data that exist are too sparse and discrepant to fully constrain the range of the methane mole fraction at various atmospheric levels. Juan Lora and colleagues point out that outputs of the IPSL atmospheric model of Titan, which track closely to observations in some respects, reflect how the model’s developers responded to this challenge: by prescribing a uniform methane mole fraction for the lowest level of the atmosphere. It is therefore important to note that __________

Which choice most logically completes the text?

• A.

  some disagreements between the model’s simulations of Titan’s precipitation and humidity and the moon’s actual precipitation and humidity are to be expected.

• B.

  even though the model’s outputs sometimes agree with observational data, Titan’s real methane mole fraction is likely higher than the methane mole fraction used in the model.

• C.

  further observations of Titan may clarify the moon’s methane mole fraction sufficiently for the model to employ a single value rather than a range.

• D.

  inconsistencies across the model’s simulations of Titan’s precipitation and humidity could be attributable to variations in the moon’s methane mole fraction.