In pcr, a. the gene sequence is determined
b. multiple copies of the dna sample are made
c. dna is destroyed so it has no value

b. multiple copies of the dna sample are made

Explanation:

Polymerase chain reaction (PCR) is a method used to make millions to billions of copies i.e. complete copies or partial copies of a specific DNA sample, allowing scientists to take a very small sample of DNA and amplify it. The new fragments of DNA that are synthesize during Polymerase chain reaction (PCR) also serve as templates to which the DNA polymerase enzyme can attach and start making DNA. The result of this attachment in a production of huge number of copies of the specific DNA segment in a short period of time.