my take

Because is a conjunction used at the beginning of a clause, before a subject and verb>>>satisfies A

Due to is a prepositional phrase that modifies a noun, commonly preceded by a form of the verb to be
So i would have gone with A

Gmat_perferct ( or maskman) , I have to say that I like the type of questions you post.

I am not an expert by any standards but here is my 2 cts.

First, let's get the difference between Because of and Due to. One of the difference is As Because of is synonymous with "for the reason of" as Due to is to "caused by".

Sentences rearranged:

1. The manufacturer has announced that it will cut production by closing its factories for two days a month because an oversupply of computer chips has sent prices plunging

2. The manufacturer has announced that it will cut production by closing its factories for two days a month due to ( caused by) plunging computer chip prices from an oversupply .

IMO - 1 ( A) seems to bring the meaning more clearly.

Pick A.

In B, "which" is wrongly modifying computer chips. it should actually modify "plunging prices".

In C, "computer chip prices have been sent plunging" is awkward.

D & E) Use "due to" only if you can substitute it with "caused by". if we do that here, the sentence becomes awkward.