SAT Question e225cf02: Transitions answer and explanation

English - Transitions - Contrast Transition
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A team of ornithologists documented patterns of conspecific brood parasitism among wood ducks (Aix sponsa) in California. The researchers observed several female wood ducks visiting dozens of nesting sites and laying eggs to be incubated by other nesting A. sponsa. Subject 7F64B, ______ visited a select few nesting sites before laying and incubating her eggs herself.
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Difficulty:Hard
Which choice completes the text with the most logical transition?