GO:0003899:   DNA-directed 5"-3" RNA polymerase activity
Catalysis of the reaction: nucleoside triphosphate + RNA(n) = diphosphate + RNA(n+1). Utilizes a DNA template, i.e. the catalysis of DNA-template-directed extension of the 3"-end of an RNA strand by one nucleotide at a time. Can initiate a chain "de novo".