Which word fits the blank? Luther responded by b------------ the letter in public.
The word that fits this blank is "burning." The question is referring to the papal proclamation, or "bull" by Pope Leo X that excommunicated Luther from the Catholic Church in 1520. This was a serious matter in the sixteenth century, as Church doctrine held that one had to receive sacraments to gain grace, or forgiveness for one's sins. Since the sacraments were essential to salvation, an excommunication, it was believed, sentenced one's soul to hell. Luther was being excommunicated for his repeated and strident criticisms of the Church and its officials, most notably in the 95 Theses he published in 1517. His main issue was the sale of indulgences, or forgiveness for sins, by Church representatives. In any case, Luther showed his contempt for Pope Leo by publicly burning the proclamation (the text of which is included in a link below) in Wittenburg in December. Shortly thereafter, he was called before the Diet of Worms to defend himself before Holy Roman Emperor Charles V. When he refused to recant at the Diet (an imperial council), he entered into the protection of German princes, whose political concerns dovetailed with Luther's religious message.