GMAT Sentence Correction (SC) | Re: The parachutelike membranes of

The parachutelike membranes of Africa's scaly-tailed flying squirrels differ from those of the flying squirrels in the family Sciuridaebecause they are attached to a cartilage rod at the elbow instead of the wrist.

A) because they are attached to a cartilage rod at the elbow instead of

B) because of being attached to a cartilage rod at the elbow rather than at

C) in their attachment to a cartilage rod at the elbow instead of being attached at

D) in that they are attached to a cartilage