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Question 126·Hard·Transitions

Researchers long assumed that the painted lady butterfly migrates only as far north as temperate Europe. A 2013 satellite-tagging study, however, revealed individuals completing a six-generation circuit that spans over 14,000 kilometres, reaching the Arctic Circle. ______ the discovery that larvae can enter a suspended metabolic state enables them to survive sub-freezing temperatures, making this extended migration biologically plausible.

Which choice completes the text with the most logical transition?