The following text is from a biography of inventor Nikola Tesla.
Tesla's alternating current (AC) system eventually prevailed over Edison's direct current (DC) system for several key reasons. AC could be transmitted over much greater distances without significant power loss. Furthermore, transformers could easily step up or step down AC voltage for different applications. These advantages made AC the standard for electrical power distribution worldwide.
What is the primary purpose of the text?
To describe Tesla's personal life and motivations
To explain why AC became the dominant electrical system
To criticize Edison's approach to electrical engineering
To argue that DC should replace AC in modern systems
Correct Answer: B
Choice B is the best answer. The text focuses on explaining the advantages (distance transmission, voltage flexibility) that made AC the worldwide standard.
- Evidence: The text lists reasons why AC "prevailed": "transmitted over much greater distances" and "transformers could easily step up or step down."
- Reasoning: These points explain the success of the AC system.
- Conclusion: The purpose is to explain the reasons for AC's dominance.
💡 Strategy: Look for the cause-and-effect relationship described (Reasons -> AC prevailed).
Choice A is incorrect because Tesla's personal life is not discussed. Choice C is incorrect because Edison is not criticized, only compared. Choice D is incorrect because the text supports AC, not DC.