Final answer:
The statement that does not explain the Spanish conquest of the Aztecs is that the Spanish outnumbered the Aztecs. The primary factors in the Spanish victory were superior military tactics and weaponry, the impact of diseases like smallpox, and alliances with other indigenous groups.
Step-by-step explanation:
The option that does not explain the Spanish conquest of the Aztecs is D.) The Spanish outnumbered the Aztecs. On the contrary, the Spanish, under Hernán Cortés, were significantly outnumbered by the Aztec forces. They succeeded for other reasons, including the devastating impact of disease such as smallpox on the native population, military tactics and weaponry advantages over the Aztecs, and forming alliances with other indigenous groups who were enemies of the Aztec Empire. This strategic collaboration and the collapse of Aztec society due to disease aided the much smaller Spanish force in successfully conquering the powerful Aztec civilization.