Passage Summary: We are unlikely to ever wipe out disease because the germs that cause them are experts at evolving to survive our medicines.

Conclusion: It is improbable that the world will ever be completely rid of disease.

Reasoning: The microorganisms responsible for most diseases are highly prolific and evolve immunities to medicines very quickly while remaining dangerous to humans.

Analysis: The statement in question serves as the main conclusion of the argument. You can identify this by noting that the second sentence provides the biological explanation for why the first sentence is true. In 'Role in Argument' questions, always check if the claim is being supported by other premises or if it is doing the supporting; here, the entire passage is built to justify this opening claim.