"I am publishing a book in the German tongue about Christian reform, directed against the pope." - Martin Luther

This excerpt best supports which of the following conclusions?

a) abuses and excesses by Muslim rulers inspired opposition to Islamic rule
b) Calvinism and other Protestant sects gained popularity by encouraging personal faith
c) counter-reformation principles took root by spreading fear and promoting persecution
d) vernacular language and the printing press drove the spread of Reformation ideas