21.

Answer and Explanation

Your Answer is

Correct Answer is A

Explanation

Sentence meaning "Some critics believe that although most parts of Cane seem to be unconnected, these parts may also be linked together by common themes and images", item A linked "v. connect" is correct. fastened "v. fasten", combined with "v. make combination", attached to "v. paste" all do not conform to the meaning of the sentence.