Answer:
A) the printing press.
This question wants to know the tool Luther used to spread his ideas.
Step-by-step explanation:
Martin Luther began to criticize the sale of indulgences by the Pope when he nailed his 95 theses in the Wittenburg Cathedral. There he started his fight. Anyway, after this action, he began to share his ideas through Germany, writing texts and exposing arguments (speaking or writing). Luther used the printing press to produce copies of his material faster and spread across the country. If he didn't use this tool, his reformation would delay establishing an audience, not only in Germany but in the rest of Europe.