18. Which of the following correctly describes a difference between RNA & DNA polymerases?
(A)RNA polymerases usually do not need a template, while DNA polymerases do.
(B) DNA polymerases usually require a primer (i.e., they can only continue a strand, not start one), while most RNA polymerases do not.
(C) RNA polymerases usually synthesize introns, while DNA polymerases synthesize cistrons.
(D)RNA polymerases polymerize 5' → 3', while DNA polymerases polymerize 3' → 5'.
(E) None of these