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.

The scientist's groundbreaking research (A) led to the development of a duel-functioning nanomaterial, (B) capable of both capturing solar energy during the day (C) and emitting stored light for illuminating spaces at night. (D)