The graph below shows the number of accurate copies of DNA produced bypolymerase chain reaction (PCR).

1. 1.    What can you conclude about cycles 18–26?

A. PCR produced accurate copies of template DNA at an exponential rate.

B. The amount of DNA produced by PCR doubled with each cycle of the reaction.

C. The DNA copies produced by PCR were not accurate copies of the original DNA template.

D. A and B only

E. A and C only

2. 1.    Based on the graph, which of the following might have happened between cycles 26-28?

A. PCR stopped producing accurate copies of the template.

B. The rate of the reaction slowed down.

C. All the template DNA was used up.

D. A and C only

E. B and C only