The scientists noted that rats suffering from the rare degenerative disease had begun to die six months earlier, even though they had shown no signs of the disease then.
(A) earlier, even though they had shown no signs of the disease then
(B) earlier, but they were not showing no signs of the disease then
(C) earlier, no outward signs of the disease had been shown in them, however
(D) earlier without any signs of the disease shown then
(E) earlier, even though no signs of it were seen in them at that time

OA after some discussion