Paraphrasing the Answer B

I read the explanations to this question and I am still confused. The correct answer says: "fails to exclude an alternative explanation for the observed effect." To "fail to exclude" is to include. That would mean "includes" or "considers" an alternative explanation. But the person in the prompt did not include or consider an alternative explanation, they concluded that it probably wasn't vinegar. That's why I quickly crossed this answer out. Please share your thoughts on paraphrasing the answer B and how this answer can be the correct answer considering how it is phrased. Thank you.