Scientists: An experimental technique for combating severe depression, deep-brain stimulation (DBS) demonstrates much promise for the long-term treatment of chronic depression. In a recent experiment, electrodes were implanted into the brains of six patients who had not responded to any currently approved treatment for depression. When an electrical current to the electrodes was switched on, four of the patients reported feeling a dramatic reduction of depressive symptoms. The depressive symptoms returned when the current was switched off.

Which of the following, if true, best supports the scientist's claim of the promising potential usage of DBS?

A. The electrode implanted during deep-brain stimulation can only be activated in a hospital setting.

B. The other two patients reported a slight reduction of depressive symptoms when the current on their electrodes was activated.

C. The operation to implant the electrodes poses a high risk of brain hemorrhage, infection or seizure.

D. In a subsequent experiment, a one hour treatment the electrodes produced sustained remission from depression in the four patients for six months.

E. Deep-brain stimulation relies on the expertise of highly skilled physicians.

OA later