The correct answer is C. the Tlaxcalans and the totonac were eager to get out from under the self-imposed rule of the Aztec.
Cortes sought alliances with these groups because they had adversarial relationships with the Aztecs and were keen to aid in their defeat in order to free themselves from Aztec dominance. Thus, they brought both military support and local knowledge that were crucial to Cortes' campaign against the Aztec Empire.