The enzyme used in polymerase chain reaction (PCR) is

The key ingredients of polymerase chain reaction are Taq polymerase which is a DNA polymerase enzyme that makes new DNA strand from the isolated DNA. It is isolated from bacterium, Thermus acquaticus. Whereas RNA polymerase is a type of enzyme that produces Primary RNA transcript from the DNA, nuclease enzyme is used to cleave the nucleic acid within the sequence called as endonuclease such as ribonuclease

So, the correct answer is 'Taq polymerase'