19. All of the following are characteristics for in vitro DNA synthesis EXCEPT: (A) DNA polymerase adds nucleotides in a 5'→ 3' direction. (B) The primer strand of DNA determines the nucleotides added. (C) Correct hydrogen bonding is the primary check of the newly synthesized DNA. (D) A primer strand must contain a free 3'-OH. (E) DNA polymerase copies the complementary strand of DNA.