Read each question carefully. Determine the best answer to the question from the four answer choices provided. How were the Spanish able to conquer two great empires with only a handful of soldiers? First, the Spanish had superior military equipment. They were protected by steel armor and had guns. The Aztecs and Incas relied on clubs, bows and arrows, and spears. Also, the Native Americans had never seen horses. They were frightened by mounted Spanish soldiers.

In addition, the Native Americans did not fight as hard as they might have. The Aztecs hesitated to attack at first because they thought the Spanish might be gods. The Incas were weak from fighting among themselves over control of their government.

Finally, many Indians died from European diseases, such as smallpox, measles, and influenza. Some historians believe that disease alone would have ensured Spanish victory over the Indians.

According to this excerpt from the text, which was the most significant factor in the Spanish conquest of the Aztecs and Incas?

A. armor
B. disease
C. guns
D. horses