The correct option is C Bracts
The actual flower of the Bougainvillea plant is small and generally white, but each cluster of three flowers is surrounded by three or six bracts with the bright colors (pink, magenta, purple, red, orange). The beauty of the flower is due to these bracts. Bougainvillea is also called as paper flower because the bracts are thin and papery. Thus, the correct answer is option C.