Arbitrageurs/Informed investors in commodities markets

The extract below is from commodities in Volume 6, Reading 46, Example 8. I’m less interested in the answer or question, and more interested in how they define A (arbitrageurs) and C (informed investors). Are informed investors equivalent to speculators? If so, the below descriptions sound identical to me, so how are informed investors, speculators and arbitrageurs different? Thanks!!! A is incorrect because arbitrageurs typically seek to capitalize and profit on mispricing due to a lack of information in the marketplace. C is incorrect because informed investors predominantly keep commodity futures markets efficient by capitalizing on mispricing attributable to a lack of information in the marketplace.

(Institute 204)

Institute, CFA. 2018 CFA Program Level II Volume 6 Alternative Investments and Portfolio Management. CFA Institute, 07/2017. VitalBook file.

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