Here is OE:
The answer is (D).
Choice (A) is incorrect. Although the first two phrases, war brewing in Europe and the industrial revolution well-established, have different structures, the thoughts are parallel. However, the third phrase, and a nascent communication age, is not parallel to the first two.
Choice (B) does not make the third phrase parallel to the first two.
Choice (C) changes the meaning of the sentence: the new formulation states that war already existed in Europe while the original sentence states that war was only developing.
Choice (D) offers three phrases in parallel form.
Choice (E) is not parallel since the first two phrases in the series are noun phrases, but saw the birth of the communication age is a verb phrase. When a word introduces a series, each element
of the series must agree with the introductory word. You can test the correctness of a phrase in a series by dropping the other phrases and checking whether the remaining phrase agrees with the introductory word. In this series, each phrase must be the object of the preposition with:
This century began with war brewing in Europe
This century began with the industrial revolution well-established
This century began with saw the birth of the communication age
In this form, it is clear the verb saw cannot be the object of the preposition with.