Ans. (b). to make the reaction go faster.
Kary Mullis discovered a thermostable enzyme, named as Taq polymerase, named after the bacterium, <em>Thermus aquaticus</em>, from which it was isolated.
Taq polymerase is used in PCR (polymerase chain reaction) to make copies of sample DNA. During PCR, after each round of amplification, the PCR mixture is heated above 90° C to unwind the newly formed DNA, permitting separation of DNA strands to act as template for next round of replication.
If one uses normal DNA polymerase in PCR, it requires addition of new enzyme after denaturation phase of each cycle as it gets denatured at high temperature. On the other hand, Taq polymerase functions properly at high temperature, eliminates the need to add new polymerase enzyme to each cycle and makes the reaction faster.
Thus, the correct answer is option (b).