IMO:A

[spoiler]IMO A;
[/spoiler]


It cannot be C, because have been been plunging refers to an action which is still continuing till date; while computer manufacturer announced is an action that happened in the past.

A is better
In choice C, which is modifying plunging; this is illogical as it should modify oversupply. It was the oversupply of computer chips that made manufacturer's announce a production cut

IMO A

IMO A.

[spoiler]A for me. What is the OA?[/spoiler]

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

A) Because an oversupply of computer chips has sent prices plunging - the verb is singular and matches oversupply. "Because" is used correctly instead of "due to"
B) Because of plunging prices for computer chips, which is due to an oversupply - which refers to computer chips or prices and the verb following it should be "are". That is not the case- Subject-Verb agreement not in order.
C) Because computer chip prices have been sent plunging, which resulted from an oversupply - who have sent the prices of these computer chips to plunge? Not clear
D) Due to plunging computer chip prices from an oversupply - Due to does not outline the cause correctly, use because instead
E) Due to an oversupply, with the result that computer chip prices have been sent plunging - Modifier "with the result..." is awkward.