A - incorrect, the use of the structure "were to develop" suggests that the action was supposed to take place but in fact it did not. Also "an increase in numbers ... came" is stylistically and logically incorrect. It is not the increase that came but the workers.
B - incorrect, the use of "with" suggests that a phrase should follow. However, there is a conjugated verb "came." Therefore, we need to use a clause.
C - incorrect, it is illogical and stylistically flawed. It is incorrect to say "increases in numbers of Chinese workers... came." It was the workers who came and not increases.
D - correct, it is correct to say that "increasing numbers of Chinese workers came ..."
E - incorrect, repeats the same mistake as answer B because there is the preposition "with" used.