Final answer:
The ovary is found only in females and is responsible for producing eggs and secreting female sex hormones.
Step-by-step explanation:
The correct answer is D. An ovary. The ovary is a reproductive organ found only in the female reproductive system. It is responsible for producing eggs (ova) and secreting female sex hormones such as estrogen and progesterone. The male reproductive system does not have ovaries, making this option unique to females.
Learn more about The presence of ovaries in females