The correct answer to this open question is the following.
What Cuauhtemoc did in hopes of holding back the Spaniards was the following.
Aztec emperor Cuauhtemoc tried to hold the Spanish invaders at all costs. He was the last ruler of the Great Aztec Empire, leading the Aztecs from 1520 to 1521. So what Emperor Cuauhtemoc did was to call for support and reinforcements to other allies in other territories to help defend the great city of Tenochtitlan, the capital of the Empire. Only its allies, the Tlatelocals, answered the call. Cuauhtemoc was captured by the Spaniards in the great city of Tenochtitlan on August 13, 1521.