The best answer is b. The king reformed the encomienda system and the Dominicans changed how they spread Christianity in Central America.
Over time, there were reforms aimed at improving the treatment of Indigenous people, notably through the efforts of the Spanish crown to reform the encomienda system, which had been subject to abuse. The Dominicans and other missionary orders also began advocating for better treatment and respect for Indigenous cultures while spreading Christianity. These efforts reflected a growing awareness of the abuses faced by Indigenous populations and a movement toward reform.