Use of Not only X but also Y
Reality unknown to/by
A. not only improves language skills but also develops the imagination by requiring the visualization of a reality previously unknown by
Incorrect use of Unknown by. Unkown by reader sounds awkward.
B. improves language skills but also develops the imagination by requiring the visualization of a reality previously unknown to
Incorrect- but signifies the contrast which is not the meaning.
C. not only improves language skills but also development of the imagination by requiring the visualization of a reality previously unknown to
Incorrect Wrong use of not only improves but also development parallelism error.
D. not only improves language skills but develops the imagination by requiring the visualization of a reality previously unknown to
but also also is missing . incorrect
E. not only improves language skills but also develops the imagination by requiring the visualization of a reality previously unknown to
Correct . Proper use of unknown to and also of Parallelism (Not only but ALso).
IMO-E