Which of the following best describes Spain's treatment of the Native Americans?

You didn't really provide any possible answers here. However, I can try and answer your question because it's very straightforward. We know that the Spanish explorers/conquerors at the time when they discovered the new America didn't really treat the Native Americans fairly, to put it mildly. In a few decades, they wiped out around 20% of the native population. Which is not a small number by any means.