Sentence Correction

In 1860, the Philological Society launched its effort to create a dictionary more comprehensive than the world had ever seen; although the project would take more than 60 years to complete, the Oxford English Dictionary had been born.

(a) would take more than 60 years to complete, the Oxford English Dictionary had been
(b) took more than 60 years to complete, the Oxford English Dictionary was
(c) would take more than 60 years to complete, the Oxford English Dictionary was being
(d) would take more than 60 years to complete, the Oxford English Dictionary was
(e) took more than 60 years to complete, the Oxford English Dictionary was about to be

OA:D

My doubt is regarding B.
B is so simple and concise, plus it is not using the confusing would as D does.
Why is then B wrong ?

Can't we, in the future, tell about two things of the past keeping both of them in simple past and still the meaning is relevant ?

D on the other hand, sounds more wrongly written to me.
One part of D is in future and the other part is in the past.

I read this sentence in another MGMAT test which was correct.
It was not long after the 1930s commenced that such baritone singers as Bing Crosby and Russ Columbo contributed to the popularization of a type of romantic, soothing singing that came to be called "crooning."
Here two things are mentioned about the past and both of them are in Simple past.
commenced and contributed.

They did not use had commenced and contributed.
Can anyone please explain, how is D the right answer and not B ??

Thanks.