usage of which

[sanketm5]

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.

(A) which includes their reducing employment, using new technology to pump oil more efficiently
(B) which includes reducing employment, using new technology to be more efficient in pumping oil
(C) which include reducing employment, using new technology to pump oil more efficiently
(D) which include the reduction of employment, their using new technology to pump oil more efficiently
(E) including a reduction of employment, their use of new technology to be more efficient at pumping oil


In the above question, "which" refers to approaches or "variety of approaches ?;
Eg- In "work of art,which was created 2 yeargs" which refers to "work of art"
In 'X of Y,which' can which refer to the entire phrase X of Y.
If so, can you illustrate.
Thanks

[RonPurewal]

There's no difference in meaning, so this is a non-issue. You're choosing between two options that are, in the end, identical.