I would go for B. The tense of B is right and it is the least awkward. The sentence descibes a sequence of events and the earlier action should be in a perfect tense (one formed with have or has). B does that. Also B keeps the meaning of the original sentence that the revisions to the test are going on but have not been completed yet.

A is a poor choice because it is out of sequence and the "after many attackes recently as dated and culturally biased" is awkward.

C. Under revision is not idiomatic. The connectors do not place the events in time order as well as the formulation in B. For receiving much recent attack is awkward.

D. This one looks promising. Because is a good connector for spelling out a reason. However, D changes the meaning of the original. The revision of the test is finished in D but is still going on in the original sentence (is being revised).

E. This one also changes the meaning of the original sentence. To be revised means the revision has not started yet.