Why Are Numerous Replication Cycles - Each Performed at Three

Multiple Choice

Why are numerous replication cycles - each performed at three difference temperatures - a necessary part of a PCR reaction?

A) The initial cycles do not produce many copies of the target sequence, but since the number of molecules produced doubles with each cycle, millions of copies are produced after 20-30 cycles.
B) The initial cycles amplify DNA slowly, but as the temperature increases, DNA polymerase works more quickly to produce millions of copies of the target sequence.
C) The bacteria used in the reaction divide with each cycle, replicating the target DNA.
D) Only non-target DNA is made during the first 10 cycles, while only cycles 11-20 specifically target the gene of interest.
E) Once the enzyme starts working, it must continue until there are no remaining nucleotides.