What was one of the significant achievements of the Inca Empire?

The significant achievement of the Inca Empire highlighted in the correct answer revolves around their remarkable architectural techniques, particularly their skill in building with stones without the use of mortar. This method allowed the Incas to create incredibly durable structures that have withstood the test of time, such as the iconic Machu Picchu and numerous other temples, fortresses, and agricultural terraces. The precision with which they cut and fit stones together is a testament to their advanced engineering capabilities and craftsmanship, resulting in structures that could endure seismic activity common in the Andes region. This achievement reflects the Inca's sophisticated understanding of materials and construction methods, showcasing their ability to adapt to and manipulate their environment effectively.

In contrast, the Incas did not invent the wheel, as they had no need for it in their mountainous terrain, and they primarily relied on human and animal transportation. Furthermore, the Inca civilization was not established on democratic principles; it operated under a sophisticated system of governance that was more autocratic, with the Sapa Inca holding ultimate authority. Finally, while the Incas had a highly developed system of record-keeping known as quipu (using knots on strings), they did not have a written language in the same form as those found in other ancient civilizations,