What Did Bartolomé De Las Casas Do to Prevent Spaniards

What did Bartolomé de las Casas do to prevent Spaniards from enslaving the American natives?

A) He led a secret rebellion, freeing many of them
B) He ordered his priests not to absolve slaveholders in the sacrament of Penance until they freed their Native American slaves
C) He started an open rebellion or civil war against his own Spanish colonizers
D) He issued civil laws forbidding the slave trade, which led to a rebellion against his rule