Answer:Option 4 - Abundant water supply.
Explanation:A culture hearth is an area where civilization developed, and the primary "pull factor" that brought people together in a culture hearth was an abundant water supply. In ancient times, water was essential for survival and the development of agriculture. The presence of rivers, lakes, or other sources of water in a region made it an ideal location for people to settle and establish a community. By gathering around a reliable water source, people were able to grow crops, raise animals, and sustain themselves, leading to the formation of early civilizations. In the case of Mesopotamia, the Tigris and Euphrates rivers provided the region with a bountiful water supply, making it a prime location for the development of one of the world's earliest civilizations.