A. stone masons fitted gigantic blocks of stone without using mortar
<em>This one is incorrect for it's a characteristic of the Incan civilization.</em>
B. built a high mountain city, probably as a retreat for nobility
<em>Same as above. Also about the Incan.</em>
C. settled in the Valley of Mexico around the year 1250
This one is correct. The valley was home of many pre-Colombian civilizations; including Teotihuacan, the Toltec, and, of course, the Aztec.]
D. found a permanent home on an island where an eagle tore apart a serpent
This is part of an Aztec myth. So this one is correct.
<h2>The correct answer is C and D</h2>