The keys to the success of the Mongolian military in the 1200s included:. a. a fleet of powerful ships. b. a single of squad of soldiers. c. organized troops on horseback. d. rifles and other advanced weapons.

c. organized troops on horseback.

Explanation:

The Mongols of Gengis Khan and his successors were extraordinary horse riders. They were great riders and had dominated effective techniques to throw arrows at enemies  or fight while riding. Their discipline, technical skills as those describe earlier, and ruthlessness were a major factor of their military successes and conquests in Asia and Europe, having finished and subjugated many kingdoms and old empires.

 C. organized troops on horse back

Mongol warrior on horseback