The following sentence contains either a single error or no error at all. If the sentence contains an error, select the one underlined part that must be changed to make the sentence correct. If the sentence contains no error, select choice E.
Whether the Sumerians a were the first people b to develop writing is c uncertain, but d theirs is the oldest known writing system. e No error
(A)
(B)
(C)
(D)
(E)