The most accurate response regarding the impact of Huayna Capac on the Inca Empire is:
Huayna Capac expanded the reach of the empire, improved infrastructure, and split the empire between two sons, leading to a civil war.
Huayna Capac was a significant ruler of the Inca Empire, known for his military conquests that expanded the empire's territories and for enhancements to the infrastructure, including roads and agricultural systems. However, his decision to divide the empire between his sons, Atahualpa and Huáscar, after his death led to a brutal civil war that weakened the empire and made it more vulnerable to Spanish conquest.