Researchers found E. coli that had mutation rates one hundred times higher than normal. Which of the following is the most likely cause of these results?A) The single-stranded binding proteins were malfunctioning.B) There were one or more mismatches in the RNA primer.C) The proofreading mechanism of DNA polymerase was not working properly.D) The DNA polymerase was unable to add bases to the end of the growing nucleic acid chain.