Answer:
The large eyed ducks had an undesirable trait, but the small eyed ducks have a desirable trait. Because the large eyed ducks had a trait that decreases their chances of survival, they wete killed. But small eyed ducks are lucky because they have a trait that increases their chance of survival. The small eyed ducks reproduce more offspring that have small eyes, but the large eyed ducks cannot because they didn't survive. This causes that the allele for large eyes in the gene pool to decrease.