What key feature identifies an Olmec civilization?

The key feature that identifies the Olmec civilization is that it is recognized as the first Mesoamerican civilization. The Olmecs, who thrived from around 1400 to 400 BCE in the tropical lowlands of south-central Mexico, laid the groundwork for many elements of later Mesoamerican cultures. They were the first to develop a complex society in the region, complete with urban centers, monumental architecture, and a distinct artistic style, which included large stone heads.

Being the first civilization to emerge in Mesoamerica means they influenced subsequent cultures, such as the Maya and the Aztec, in areas such as political organization, religious practices, and even artistic techniques. The concept of a "civilization" typically includes advanced societal organization, architecture, and cultural achievements, all of which the Olmecs established and exemplified. This foundational status is crucial for understanding the progression of civilization in the region.

Other features listed, such as architecture and agriculture, were certainly part of Olmec society, but they were not unique to the Olmecs and don't singularly define their civilization’s identity in the way that being the first Mesoamerican civilization does.