What negative impact resulted for the Inca Empire when Huayna Capac divided the empire between two of his sons?

The resulting power struggle helped the Aztecs conquer the Inca.

The resulting power struggle helped the Spaniards conquer the Inca.

The empire lost the territories that Huayna Capac had recently acquired.

The empire split into two smaller empires, one northern and one southern

Question

What negative impact resulted for the Inca Empire when Huayna Capac divided the empire between two of his sons? 

The resulting power struggle helped the Aztecs conquer the Inca. 

The resulting power struggle helped the Spaniards conquer the Inca. 

The empire lost the territories that Huayna Capac had recently acquired. 

The empire split into two smaller empires, one northern and one southern