Rock samples has been dated to be 3.47 billion years old and thus is evidence

(A) has been dated to be3.47 billion years old and thus is
(B) has been dated at 3.47 billion years old and thus
(C) have been dated to be3.47 billion years old and thus are
(D) have been dated as being3.47 billion years old and thus
(E) have been dated at 3.47 billion years old and thus are

OA is E
I can't really decipher what the answer is. But I need more explanation on Option E. An Expert contribution would be highly appreciated. Thanks a lot