Answer:
Option D, the females choose mates
Step-by-step explanation:
This is a common way to fertilize in animals where male put in efforts to allow the female to choose their partners. Here, in this case the male ducks are of different bright colors thus they would compete among themselves to attract the female ducks for mating. Therefore, a female duck gets the opportunity to choose the best partner for itself. This is a way of natural selection to fertilize.
Hence, option D is correct.