Directions: The given sentence is divided into four parts A, B, C, and D. Choose the part that contains an error as your answer. If the sentence is error-free, mark 'No error' as your answer.

Have stringent regulatory frameworks been in place (A) before the proliferation of high-frequency trading, (B) the 2010 flash crash might have been prevented, (C) potentially preserving market stability and investor confidence. (D)