Directions: Read the sentence given below and identify the two parts of the sentence that contain a grammatical/contextual error. If none of the parts of the sentence has an error, select "No error" as your answer.

Fast radio bursts, intense but briefly flashes (A) of radiation, is invisible to the naked eye (B) but can outshine everything in the sky for a fraction (C) of a second, originating from distant galaxies. (D)