LSAT Practice Test

The conclusion mentioned in the question must rely on accurate data to be valid. If the data presented is inaccurate, then the conclusion drawn from it would also be unreliable. Therefore, assuming the accuracy of the data is essential to justifying the conclusion.

Options A, B, and D do not directly address the necessity of accurate data to justify the conclusion. An unbiased study, the absence of external factors, or the expertise of the environmentalist might be important for other reasons, but they are not as critical to justifying the conclusion as the accuracy of the data itself.