The assertion is TRUE as the context clearly states that in PCR, 'a very small amount of DNA can be exponentially amplified to generate thousands to millions of copies.' The technique uses a 'heat stable DNA polymerase enzyme' to make new strands of DNA. The reason is also TRUE as the context confirms that 'DNA polymerase typically used in PCR is called Taq polymerase.' However, the reason is NOT the correct explanation of the assertion because merely stating that PCR uses Taq Polymerase does not explain WHY or HOW PCR can amplify small amounts of DNA. The actual explanation would involve the thermal cycling process (denaturation, annealing, extension) and the role of primers, not just the name of the enzyme used.