Which technological development contributed most directly to the success of the protestant reformation

This question should read: 
Which technological development contributed most directly to the success of the Protestant Reformation:
(1) astrolabe (3) wheel
(2) compass (4) printing press

The answer is 4 - the printing press. 
The development of the printing press allowed documents to be printed in bulk. Before this, all documents had to be duplicated by hand. The document that was reprinted and spread to the "common man" was the Bible. Before this, only priests had access to the bible so they could interpret it as they chose. After the development of the printing press, anyone could gain access to a copy of the bible.