Which monarch freed the serfs

What would a student most likely use if he or she wanted to consult a secondary source

Between 1518 and 1548, spanish conquistadores conquered most of the new world, motivated by the a) desire for scientific knowledge. b)  to urge to claim more territory for spain. c) belief that an all-water western route to the orient existed. d) desire to advance national glory, serve god, and seek personal wealth.

The social contact theory states that