Explanation:
Transcription is the process by which the information in a strand of DNA is copied into a new molecule called messenger RNA (mRNA). The segments of DNA are transcribed into RNA molecules that encode proteins are said to produce messenger RNA.DNA contains the genetic information of an individual organism which is transferred to the newly synthesized mRNA as it contains the cistron. Gene that codes for a particular protein or enzyme is also called a cistron. It forms the largest element in the gene that encodes for a polypeptide gene. mRNA can be monocistronic or polycistronic.Hence, the correct option is (A).