The dominance of Spanish and Portuguese in Latin America can primarily be attributed to the historical context of colonization and the subsequent policies implemented by the colonial powers. Among the options you provided, the most accurate reason would be:
B. Missionaries used Spanish and Portuguese languages as part of their conversion of Indigenous peoples.
During the colonization of Latin America, both the Spanish and Portuguese empires sent a significant number of missionaries to convert Indigenous populations to Christianity. This process involved the teaching of the Spanish and Portuguese languages, which were used as a medium for religious instruction. Over time, these languages became entrenched in the social, political, and economic structures of the region.
While there may have been aspects of indigenous people seeing European languages as superior (option A) or the indigenous languages lacking certain vocabulary (option C), these ideas are less central to the historical reasons for the dominance of Spanish and Portuguese compared to the role of missionary efforts and colonial governance.