Could someone please explain this one? Why it's E, not C?

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Could someone please explain this one? Doesn't only one flight have multiple Saturdays in between?

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Could someone please explain this one?

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Wouldn't the inability to detect methane in the atmosphere (C) be the answer? The right answer (B) says that not all living beings have the ability to produce methane, but couldn't "not all" still mean that 99.9% of living beings could (and hence NOT weaken the argument)

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