The correct answer is option 4: Ovary. Birds, like other animals, have reproductive organs called gonads. In females, the gonads are called ovaries and they are responsible for producing eggs. This is an essential aspect of bird reproduction as they lay eggs rather than giving birth to live young. The ovary is part of the bird`s reproductive system, and it plays a crucial role in the process of reproduction. The other options mentioned are not correct. While birds do have kidneys (option 1), lungs (option 2), and testes (option 3), these are not unique to birds and are present in many other animals as well. It is important to understand the specific characteristics and adaptations of different species when studying biology.