The activist concludes that irradiated food is not safe for human consumption. Why? Because, despite the fact that five studies concluded that irradiated food is safe for human consumption, these studies were found to be seriously flawed in their methodologies.
In essence, the activist concludes that the food is not safe for human consumption because five studies which found it was safe used flawed methods to prove this claim. In other words, the activist takes these studies' failure to prove the claim as evidence that the claim must be incorrect.
This is directly restated by answer choice (A), making it our correct answer. It is entirely possible that the results of the studies were correct even if the methods they used to reach the results were flawed.
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