roofreading of the DNA by DNA polymerase occurs A) Immediately after a mismatched base is added B) After 100 base pairs are added C) After 1000 base pairs are added D) After the entire DNA strand is replicated

The correct answer is A) Immediately after a mismatched base is added. DNA polymerase has a proofreading function that checks the newly added base pairs for errors. If a mismatched base is added, the enzyme can detect this error and replace the incorrect base with the correct one. This process occurs immediately after the base is added, ensuring the accuracy of DNA replication.