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, a royal 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
ceremonial site, a royal estate, or to protect themselves from intruders.