Question 158·Medium·Central Ideas and Details
Many people attribute the success of the ancient city of Petra solely to its impressive rock-cut architecture, but recent archaeological evidence suggests its prosperity depended even more on its sophisticated water-management system. By channeling flash-flood runoff through hidden canals and storing it in massive cisterns, the Nabataeans ensured a reliable supply of water in an otherwise arid landscape. Without this infrastructure, the city’s famous façades could not have been sustained, nor could Petra have become a bustling trade hub.
Which choice best states the main idea of the text?
For main-idea questions, first quickly paraphrase the passage in 1–2 simple sentences, focusing on what the author is saying overall rather than on small details. Then eliminate any answer choices that introduce new information, focus on minor details, or shift to a different time period or topic; choose the option that best matches your paraphrase and reflects the main point emphasized in both the beginning and the end of the passage.
Hints
Focus on the contrast in the first sentence
Look closely at the words after the word "but" in the first sentence. What does the author say Petra’s prosperity actually depended on?
Use the middle details to support the main point
The passage describes how the Nabataeans channeled flash-flood runoff and stored it in cisterns. Ask yourself: Why is the author giving these details? What bigger point are they supporting?
Check the last sentence for the author’s conclusion
The last sentence explains what would not have been possible without the thing the author is emphasizing. What is that, and how does it relate to Petra’s success?
Step-by-step Explanation
Identify what the question is asking
The question asks for the main idea of the text. That means you need a choice that summarizes the overall point of the whole passage, not a small detail.
Summarize the passage in your own words
Paraphrase the passage:
- First sentence: Many people think Petra’s success was only because of its rock-cut architecture, but new evidence says its prosperity depended even more on its water-management system.
- Middle: It describes how they channeled flash-flood water through canals and stored it in cisterns to have a steady water supply in a very dry place.
- Last sentence: Without this water system, the famous façades and Petra’s role as a busy trade hub would not have been possible.
Together, these ideas show that Petra’s real success came from how it managed water in the desert, not just from its architecture.
Extract the central contrast and cause
Notice the structure:
- There is a contrast between what “many people” think (architecture) and what the author says is more important (water system).
- The passage explains that the water system allowed both the façades and the trade hub to exist. So the main idea is about what truly made Petra thrive: the engineered water system in an arid environment.
Match the summary to the best answer choice
Now compare each option to your summary:
- A talks about when the façades were carved using dating methods — the passage never mentions dates or new dating technology.
- B says the Nabataeans copied techniques — the passage doesn’t mention copying or other cultures.
- D talks about modern engineers using Petra’s canals — the passage doesn’t mention modern engineering projects.
- C states that Petra thrived mainly because its people created an advanced system to capture and store water in the desert, which matches the passage’s focus on the water-management system as the true source of Petra’s prosperity.
So the correct answer is C) Petra thrived primarily because its inhabitants engineered an advanced system to capture and store water in the desert.