Answer:
By proofreading activity of DNA polymerase.
Step-by-step explanation:
Mutations are defined as permanent, inherited changes in the nucleotide sequence of genetic material. Mutations can be caused by errors during the DNA replication, when the enzyme DNA polymerase adds a wrong nucleotide to the growing DNA strand.
When a wrong nucleotide or base is detected (by proof-reading activity of DNA polymerase) in the growing chain, DNA replications halts and the incorrect base is removed by the enzyme's exonuclease activity. Then, DNA polymerase again starts to replicate the DNA, using its polymerizing activity.
Thus, the errors can be prevented during DNA replication by DNA polymerase as it shows both polymerizing, exonuclease and as well as proof-reading activity.