Final answer:
DNA polymerase proofreads during replication by checking if the newly added base pairs correctly with the template strand. It removes incorrect nucleotides and replaces them with correct ones.
Step-by-step explanation:
During DNA replication, DNA polymerase proofreads by checking whether the newly added base has paired correctly with the base in the template strand. If it is the right base, the next nucleotide is added. If an incorrect base has been added, the enzyme makes a cut at the phosphodiester bond and releases the wrong nucleotide. This proofreading process is performed by the exonuclease action of DNA polymerase. Once the incorrect nucleotide has been removed, it can be replaced by the correct one.