Why does a new DNA strand elongate only in the 5' to 3' direction during DNA replication? (A) DNA polymerase begins adding nucleotides at the 5 ' end of the template. (B) The polarity of the DNA molecule prevents addition of nucleotides at the 3' end. (C) Replication must progress toward the replication fork. (D) DNA polymerase can add nucleotides only to the free 3' end.