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 one of the last great Sapa Inca rulers, known for significantly expanding the Inca territory and implementing improvements in infrastructure, such as road networks that facilitated communication and trade across the vast empire. However, upon his death, he divided the empire between his two sons, Atahualpa and Huáscar, which ultimately led to a civil war as they vied for control of the empire.