SC Archive | Re: It is difficult to study the depths of the Arctic Ocean

It is difficult to study the depths of the Arctic Ocean, primarily due to the icy
surfacebeing difficult to penetrate using current technology.

(A) primarily due to the icy surface being
(B) primarily due to the icy surface is
(C) because the primarily icy surface is
(D) primarily caused by the icy surface
(E) primarily because the icy surfaceis