The correct answer is B) These so-called Christians set about stealing from the people and murdering them.
The excerpt from the passage that best supports Bartolomé’s argument that the Spanish were not behaving as Christians should is "These so-called Christians set about stealing from the people and murdering them."
Bartolomé de las Casas (1484-1566) was one of the first friars that defended the Native American Indians from the atrocities and brutal practices of the Spanish conquerors. Bartolomé belonged to the Dominicans, and since he arrived in the Americas he firmly opposed the horrors and barbarism of the Spanish conquerors. He can be considered a supporter of the Indian's rights.