Explanation
Correct answer: B.
Choice B is the best answer because it most accurately states the main purpose of the text. The text begins by noting that little is known about juvenile sea turtles during their oceanic stage, establishing this as an understudied area. The text then describes a study in which researchers tagged and released six juvenile green sea turtles and reports the findings: most turtles drifted passively with currents, while two swam against them. Therefore, the main purpose of the text is to summarize research on an understudied stage of sea turtle development.
Why the other choices are wrong
Choice A
Choice A is incorrect because although the text mentions that understanding migratory patterns is important for conservation, it does not describe any conservation efforts, successful or otherwise; instead, the text summarizes research findings about a stage of sea turtle development.
Choice C
Choice C is incorrect. Although the text notes that adult sea turtles are well studied while juveniles are not, it does not compare the migratory behavior of adults and juveniles; instead, the text focuses solely on findings about juvenile turtles.
Choice D
Choice D is incorrect. Although the text briefly mentions that two turtles swam against currents and speculates that they may have done so in search of foraging grounds, this is a single detail within the text’s broader summary of the study, not the main purpose of the text as a whole.