Passage Summary: We have the tech for clean hydrogen cars but nowhere to fill them up; however, history suggests that if people want them, the gas stations of the future will pop up very quickly.

Conclusion: A national system of hydrogen fuel stations is likely to appear and expand quickly.

Reasoning: Even though the infrastructure doesn't exist now, history shows that fuel systems can develop rapidly in response to consumer demand, just as gasoline stations did a century ago.

Analysis: To identify the conclusion, look for the claim that the rest of the passage is trying to prove. The word 'however' signals a shift toward the author's main point: the prediction that the infrastructure will grow rapidly. The final sentence serves as a premise, using a historical analogy to support that prediction. Focus strictly on the structural role of that specific prediction rather than evaluating whether the analogy to gasoline is actually a good one.