The Polymerase Chain Reaction (PCR)technique Could Be Developed Only After

The polymerase chain reaction (PCR) technique could be developed only after the discovery of bacterial enzymes that were able to withstand high temperatures.Why was it necessary to use such enzymes?

A) Only bacterial DNA can be copied using the PCR method,so bacterial enzymes were necessary.
B) Bacterial enzymes can bind to DNA outside of a cell.
C) DNA can be cut into fragments only at high temperatures.
D) The temperature required to separate DNA strands during PCR degrades most normal enzymes.