Every fall Croton' s jays migrate south. The jays always join flocks of migrating crookbeaks with which they share the same summer and winter territories. If a jay becomes separated from the crookbeaks it is accompanying, it wanders until it comes across another flock of crookbeaks. Clearly, ttherefore, Croton' s jays lack the navigational ability to find their way south on their own. Which of the following, if true, most strengthens the argument?
A: Croton's jays lay their eggs in the nests of crookbeaks which breed upon completing their southern migration
B: Species other than Croton's jays occasionally accompany flocks of migrating crookbeaks
C: The three species most closely related to crookbeaks do not migrate at all
D: In the spring, Croton's jays migrate north in the company of Tattersall warblers
Choose A, B, C or D as your solution.
D