Passage Summary: A consumer advocate is worried that 'pharmaceutical' plants will cross-pollinate with regular food plants, accidentally putting medicine into our dinner.

Conclusion: Genetically engineering crops to produce pharmaceuticals creates a risk that these drugs will enter the human food supply.

Reasoning: Pollen from these 'drug-crops' can drift into nearby fields of the same species, fertilizing ordinary crops and causing them to produce the drugs as well.

Analysis: To weaken this argument, we need to find a 'block' between the cross-pollination and the actual consumption of the drugs. The advocate assumes that if the plant is fertilized, the resulting crop will be eaten by humans. What if the specific species used for these drugs are not ones that humans eat? Or what if the drug is only produced in the leaves, but we only eat the roots? Look for an answer that suggests the cross-pollinated plants won't actually result in drugs being ingested by the public.