Which led to the decline of the Aztec empire?

None of the above.

a) This would pertain to the Aztec monetary system, but that system was not as debilitating as maintaining hostile relations with their neighbors (who, in turn, allied themselves with the Spanish when they arrived).

b) By mandate of the Pope, the Portuguese were to stay east of a certain longitude that cleaved thru South America. That section of South America became Brazil. No attempts were made to go as far west as present-day Mexico.

c) South America is south of Central America, the patch of land situated between southern Mexico (south of where the Aztecs lived) and South America. Consequentially, South Americans had no contact w/ the Aztecs &, thus, no way to develop a resentment towards them.

d) The Aztecs & the English never met.

Sincerely Non of the above

SMALLPOX OR "VARICELA" was the cause of the decline of that empire, and the cause of the death of all North American tribes.

Tenochtitlan (actual Mexico City) was the Capital of Aztec Empire, his population was HUGE, Cortez, the first time when he saw the city from the mountains said, "it's bigger then London" and in that time London was the most inhabited city of Europe.

In 1520-1521, an outbreak of smallpox swept through the population of Tenochtitlan and was decisive in the fall of the city. It is estimated that between 10% and 50% of the population fell victim to this epidemic.

Subsequently, the Valley of Mexico was hit with two more epidemics, smallpox (1545-1548) and typhus (1576-1581). The Spaniards, to consolidate the diminishing population, merged the survivors from small towns in the Valley of Mexico into bigger ones. This broke the power of the upper classes, but did not dissolve the coherence of the indigenous society in greater Mexico.

The population before the time of the conquest is unknown and hotly contested,but disease is known to have ravaged the region; thus, the indigenous population of the Valley of Mexico is estimated to have declined by more than 80% in the course of about 60 years

That Means, in every 5 aztecs or america natives, 4 died.

That's the MAIN CAUSE OF THE FALL OF THE AZTEC EMPIRE & all the North America Natives from the Atlantic to the Pacific.

Wow. Several reasons, none of which are mentioned here.

Two primary reasons were a Spanish alliance with the Tlaxcalans, which overwhelmed the Aztec defenses; and a series of epidemics, which wiped out roughly 80% of the population.

Regarding the four choices above: there is no evidence of A, they never had any contact with any Portugese, or for that matter any peoples in South America, nor were there any English colonists in their sphere of influence. Which was limited to what is now central Mexico. None of the four answers make any sense.

http://search.yahoo.com/search?p=decline+of+the+Az...

none of above...

the great empires fall due to "ego war" and nothing else.

Disease...