Final answer:
The false justification for European conquest of the Americas is 'Respecting native sovereignty,' as European colonization was marked by the conquest and subjugation of indigenous peoples, not the respect of their sovereignty.
Step-by-step explanation:
Among the justifications European powers used for the conquest and colonization of the Americas, the false one is d) Respecting native sovereignty. European colonization was driven by various motives, with economic, religious, and cultural justifications commonly cited. These include a) "Civilizing" the indigenous population, which is related to the belief in a civilizing mission, b) Spreading Christianity as part of religious evangelism, and c) Expanding economic opportunities such as gaining access to raw materials and establishing trade routes. However, the concept of respecting the sovereignty of the native populations was not a consideration, as colonization often involved the conquest and subjugation of indigenous peoples.