The transition from hunting-gathering to settled agriculture marks the beginning of the:

Mesolithic Age
Paleolithic Age
Iron Age
Neolithic Age

The correct answer is: D) Neolithic Age.

The Neolithic Age, or New Stone Age, is a period in human prehistory distinguished by the original development of agriculture, which enabled the transition from hunting and gathering to more sedentary living. The Neolithic Age began around 10,000 years ago in the Fertile Crescent, a region of the Middle East where the first civilizations developed.

The Paleolithic Age, or Old Stone Age, is a period in human prehistory that lasted from the earliest use of stone tools by hominins 2.58 million years ago to the end of the Pleistocene epoch 11,700 years ago. The Paleolithic Age is characterized by the use of stone tools, the development of hunting and gathering techniques, and the beginning of human migration out of Africa.

The Mesolithic Age, or Middle Stone Age, is a period in human prehistory that lasted from the end of the Paleolithic Age to the beginning of the Neolithic Age. The Mesolithic Age is characterized by the development of new technologies, such as the bow and arrow, and the beginning of the transition from hunting and gathering to agriculture.

The Iron Age is a period in human history that began with the discovery and use of iron. The Iron Age is characterized by the development of new technologies, such as iron tools and weapons, and the beginning of the development of complex societies.

In conclusion, the transition from hunting-gathering to settled agriculture marks the beginning of the Neolithic Age.