9. Scientists used ultrafast X-ray pulses to directly visualize the DNA photorepair process. The probability of bond-rearrangement events was observed to increase gradually over a timescale of approximately 500 ns. Which of the following statements is incorrect?
(A) Molecular bond elongation occurs on a timescale of approximately 500 ns.
(B) Molecular bond elongation occurs on a timescale of approximately 500 fs.
(C) Although molecular bond vibrations occur on ultrafast timescales, the concentration of reaction products may require a much longer time to increase to a detectable level.
(D) The presence of multiple reaction barriers allows reactant molecules that have crossed a barrier to return via reverse reactions.