To determine how paragraphs 6-8 contribute to the development of ideas in the passage, we need to analyze the content and focus of those specific paragraphs. Without seeing the exact text of those paragraphs, we can generally interpret their contribution based on the options provided:
A. If paragraphs 6-8 discuss historical threats that have always existed for big trees, then choice A could be the correct answer.
B. If they focus on new or emerging threats to big trees and highlight current issues facing them, then option B would be more appropriate.
C. If the paragraphs suggest that logging is not a significant issue compared to others affecting big trees, then choice C would apply.
D. If these paragraphs compare the ecological roles of understory plants with big trees, implying equal importance, then D would be the correct choice.
To choose the best answer, clarify the main focus of paragraphs 6-8. If they indicate fresh or ongoing challenges unique to the current time, choose B. If they bring attention to longstanding issues, A might be more appropriate. If they imply something about logging or understory plants, assess the emphasis on those topics to make the final decision.