Based on the text, what can most reasonably be inferred about the development of tool-making proficiency in New Caledon…

According to the passage, isolated juvenile crows instinctively fashioned rudimentary hooked tools without exposure to adults, demonstrating an innate baseline capacity for tool manufacture. However, their implements lacked the precise curvature and tapering found in wild crows' tools, and this difference persisted despite extensive individual trial-and-error experience. Synthesizing these two findings leads to the inference that while the basic drive and ability to make tools are innate, attaining the advanced refinement observed in the wild depends on social contact with experienced adult crows.

Therefore, Choice B is the correct answer.

Choice A is incorrect because the passage explicitly states that isolated juveniles successfully and instinctively created functional implements to retrieve food without parental demonstration.

Choice C is incorrect because the text notes that the gap in tool quality persisted even after the isolated crows accumulated months of individual trial-and-error experience, indicating that solo practice was insufficient for structural precision.

Choice D is incorrect because the difference between the isolated crows and wild crows was specifically in the structural refinement (consistent tapering and hook curvature) of the tools themselves, not merely in their motivation to forage.