Question

select the misplaced or dangling modifier.
because it offered unprecedented access to books, the printing press is considered to be one of historys most important inventions by many.

Explanation:

The phrase "by many" is a misplaced modifier. It is intended to modify "considered" (indicating who holds the belief about the printing press), but its position at the end of the sentence incorrectly appears to modify "inventions" instead.

Answer:

"by many"