Answer:
A
Explanation:
Early groups of hunter gatherers continued to move south. They would eventually settle down in areas such as central america, with civilizations such as the Aztecs and the Mayans.
The correct answer is 4 :to reduce the formation of air bubbles
<em>Answer: Plains occur as lowlands along the bottoms of valleys or on the doorsteps of mountains, as coastal plains, and as plateaus or uplands. In a valley, a plain is enclosed on two sides, but in other cases a plain may be delineated by a complete or partial ring of hills, by mountains, or by cliffs.</em>