Which sentence:or sentences have correct parallel structure? While thousands of people hike the Inca trail to visit Machu Picchu, no one really knows if the Incas built the ancient mountaintop complex as a ceremonial site, aroyal estate, or a military fortress. While thousands of people hike the Inca trail to visit Machu Picchu, no one. really knows if the Incas built the ancient mountaintop complex as a ceremonlal site, a royal estate, or to protect themselves from intruders.

The first sentence has correct parallel structure: "as a ceremonial site, a royal estate, or a military fortress." Each item in the list maintains the same grammatical format, creating a smooth and coherent flow. In contrast, the second sentence breaks this parallelism with the phrase "to protect themselves from intruders," which introduces inconsistency in the structure. Maintaining parallel structure isn’t just a grammar rule—it's a readability booster! When you use parallelism, you make your writing more engaging and easier for readers to follow. It’s like a rhythmic dance for your sentences; they keep the same beat, making your ideas shine with clarity and style. So, next time you write a list, keep it in harmony!