Although DNA replication of one cell involves billions of nucleotides,why is this process so accurate?

A)DNA primers can replace any mistakes in base-pairing
B)RNA polymerase corrects any mistakes before doing RNA transcription
C)Unwinding the double helix would remove any mistakes in base-pairing.
D)DNA polymerase proofreads and corrects mistakes in base-pairing.
E)Semiconservative replication means that the process is very careful and conservativE.