For your classmate Anton's research project on Mesopotamia, he should focus on the Sumerians, Akkadians, Babylonians, or Assyrians, as these are the civilizations that flourished in that region, often referred to as the "Cradle of Civilization."
Among the options you provided (Chinese, Greek, and Mesoamerican), the Greeks would be the most relevant for understanding the influences of ancient civilizations and their contributions to topics like philosophy, governance, and science, as they were directly impacted by Mesopotamian advancements. However, it is important to note that the Greeks were not part of Mesopotamia; rather, they were influenced by its earlier civilizations.
Ultimately, for a thorough understanding of Mesopotamia itself, he should focus on the indigenous cultures and civilizations of the area rather than comparing them to other distinct civilizations like the Chinese, Greeks, or Mesoamericans.