19. During DNA synthesis, (A) The nascent DNA is always synthesized in the 5' to 3' direction, as DNA polymerases can add a nucleotide only to the 3' end of a DNA strand (B) The initiation of DNA synthesis upon a primer of DNA and the subsequent attachment of the second deoxyribonucleoside triphosphate (C) On the lagging (forward) strand, the DNA is synthesized continuously (D) On the leading (retrograde) strand, the DNA is synthesized in short (1-5 kb) fragments, the so-called Okazaki fragments (E) An enzyme capable of polymerizing DNA in the 3' to 5' direction does not exist in any organism.