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.
This response correctly highlights Huayna Capac's role in expansion and infrastructure improvement, as well as the significant consequences of dividing the empire between his sons, which ultimately led to a civil war. The other options contain inaccuracies, such as attributing the split of the empire to Spanish colonizers.