Which invention aided martin luther in his struggles against the roman catholic church?

Luther also sent a copy to Archbishop Albert Albrecht of Mainz, calling on him to end the sale of indulgences. Aided by the printing press, copies of the 95 Theses spread throughout Germany within two weeks and throughout Europe within two months.

Explanation:

answer; i believe the correct answer is (4) flip a coin as each participant arrives,heads indicates assignment to the first group: tails indicates assignment to the second group;