Final answer:
The Nīnole Hills, representing the ancient surface of Maunaloa, are located in the district of Ka'ū.
Step-by-step explanation:
The Nīnole Hills, which are part of the ancient surface of Maunaloa, are located in the moku (district) of Ka'ū. These hills encompass historic and cultural significance to the people of Hawai'i. The question pertains to the specific district in which these storied pu'u (hills) are found, offering insight into both the geography and the history of Hawaii. Such knowledge is essential to understanding the broader cultural and historical context of the Hawaiian islands, which have been shaped by their volcanic origins and a complex colonial history.