Refer to the Figure, Which Shows the Process of in Vitro

Refer to the figure, which shows the process of in vitro evolution of a new RNA molecule. The intended selection occurred

A) at the stage of PCR amplification.
B) at the stage of reverse transcription.
C) during transcription to RNA.
D) because the experimenters chose the RNA molecules with the highest ligase activity.
E) because the experimenters chose the DNA molecules with the highest ligase activity.