$A$ : Single $DNA$ dependent $RNA$ polymerase catalyses transcription of all types of $RNA$ in all except bacteria.
$R$ : Structural genes in bacteria are monocistronic.

• A

  Assertion and Reason both are correct and also correct explanation.

• B

  Assertion and Reason both are correct but not explanation of assertion.

• C

  Assertion is correct, but Reason is incorrect.

• D

  Both Assertion and Reason are incorrect.