The correct answer is D) Printing Press.
The invention of the printing press was one of the most influential inventions of the 15th century. This allowed for a dramatic increase in the amount of books available to European citizens. Before this time, ownership of books was rare for common citizens as books had to be written/copied by had. After this invention, more people gained access to important works (like the Bible). This ultimately helped lead to a dramatic increased in the literacy level in Europe.
