GMAT Sentence Correction (SC) | In attempting to solve the problems caused by a lowering of

In attempting to solve the problems caused by a lowering of the price of oil, oil companies operating in the North Sea have taken a variety of approaches,which includes their reducing employment, using new technology to pump oil more efficiently from smaller fields, and finding innovative ways to cut the cost of building and operating platforms.

Errors: 1)includes refer to approaches => should beinclude ; 2) their is ambiguous

With this knowledge lets go to answer choices

(A) which includes
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