42. Which of the following best describes the complete sequence of steps occurring during every cycle of PCR? 1. The primers hybridize to the target DNA. 2. The mixture is heated to a high temperature to denature the double-stranded target DNA. 3. Fresh DNA polymerase is added. 4. DNA polymerase extends the primers to make a copy of the target DNA. (A) 2, 1, 4 (B) 1, 3, 2, 4 (C) 3, 4, 1, 2 (D) 3, 4, 2