The Sumerians, who founded the first cities, not only invented writing, created poetry and the rule of law, and were also extraordinary craftsmen.
(A)
and were also extraordinary craftsmen.
(B) but
were also extraordinary craftsmen.
(C) but also were extraordinary craftsmen.
(D) but also fashioned
extraordinary crafts.
(E)
and also fashioned
extraordinary crafts.
The correct answer is C. A. Incorrect idiom. The correct idiom is "not only X ... but also Y"; additionally, the verb "were" should follow "also"--not precede it.
B. Incorrect idiom. The correct idiom is "not only X ... but also Y"; the verb "were" (i.e., the beginning of Y) should therefore follow "also."
D. Meaning distortion. The original meaning is that the Sumerians were extraordinary craftsmen; this is not the same as fashioning extraordinary crafts.
E. Meaning distortion, as in D. Additionally, incorrect idiom as in A.