Passage Summary: A magazine said a chemical called Vexone only kills one type of cockroach. A letter writer disagrees, saying their product uses Vexone and it works on every single type of cockroach found in North America.

Reasoning: The letter writer claims Vexone is effective against all North American cockroach species, citing a decade of use and their own product studies.

Analysis: Since this is an 'EXCEPT' question regarding conflicts, four choices will contradict the letter writer, and one will be consistent with their claims. The letter writer's stance is absolute: Vexone works on all North American species. We should look for an answer that aligns with this broad claim or at least doesn't deny it. The writer is very confident, so any statement suggesting Vexone is limited in scope will be a conflict.