RNA polymerase transcribes only one strand of a DNA segment, even though the DNA is double-stranded. Read the Assertion and Reason below on why transcription is restricted to a single strand, and choose the correct option.

• Assertion (A): Within a transcription unit, only one of the two DNA strands (the template strand) is transcribed into RNA.
• Reason (R): If both strands were transcribed at the same time, the two RNA molecules formed would be complementary to each other and would pair into a double-stranded RNA that could not be translated into protein.