Final answer:
Gutenberg's Press, improved by Johannes Gutenberg, was the Renaissance invention that facilitated the Reformation by allowing the efficient spread of critical ideas and reformist literature. So the correct option is D.
Step-by-step explanation:
The Renaissance invention that helped pave the way for the Reformation was D. Gutenberg's Press. The printing press, significantly improved upon by Johannes Gutenberg, played a pivotal role in disseminating ideas quickly and efficiently. Its impact on the Reformation was profound as it enabled critics of the Church, like Martin Luther, to publish works calling for reform.
Gutenberg's printing press not only facilitated the spread of classical texts that inspired the Renaissance and humanism but also laid the groundwork for challenges to the Catholic Church's authority, which Martin Luther and other reformers capitalized on.