What kept nearly an entire generation of chinese students from receiving an education

c: Columbus presents the view that the native people were beneficial to the Spanish.

Explanation:

Most questions like these you just have to read the beginning, end, and who it's from and to.  The quote at the end "and they were of great service to us" is the most supporting evidence for what Columbus wanted to talk about. There is no talk of conflict (no a), no interference (no b), and although peace (no d) might have happened, Columbus uses "service to us", which is benefitting him so C is the only answer.