Correct Answer: Ovary

Solution : The correct option is Ovary.

Most birds have a single ovary on their left side. During development, the right ovary regresses and becomes non-functional. There are several hypotheses as to why this is the case. According to one theory, it is an adaptation for flying. A solitary ovary decreases the weight of the bird, allowing it to fly more effectively. Another idea is that it evolved to safeguard the eggs. Because the left ovary is farther distant from the heart, the eggs are less likely to be destroyed in the case of a fall.