Final answer:
The 'city of gold' that de Niza thought he had seen was actually b. a poor Zuni town, not the fabled El Dorado filled with riches.
Step-by-step explanation:
The "city of gold" that de Niza had seen ended up being B) a poor Zuni town. While the Spanish were successful in finding vast amounts of silver in places like Potosí in South America, their quests for cities of gold often led to disappointment.
The legend of a city of gold—also referred to as El Dorado—captivated many explorers. However, the fabled riches remained elusive, and many expeditions, such as that of Francisco Vázquez de Coronado led by de Niza as a guide, ultimately found native settlements like the Zuni pueblos, which were not composed of gold but were nonetheless significant indigenous communities with their own wealth and complexities.