Passage Summary: A plant disease causes spots on tomatoes, but a copper spray fixes it. Therefore, the speaker concludes the disease must have been caused by a lack of copper in the first place.

Conclusion: Late blight is caused by a deficiency of copper in a tomato plant's mineral intake.

Reasoning: Applying a copper solution to plants affected by late blight is an effective way to treat the disease.

Analysis: This argument commits a classic 'cause versus cure' fallacy. It assumes that because a substance cures a condition, the absence of that substance must have caused the condition. To parallel this flaw, look for an answer choice that identifies a successful treatment and then incorrectly concludes that the problem was a deficiency of that specific treatment.