Answer:
The correct answer is B. Papilla.
Step-by-step explanation:
In birds, the reproductive organs are located inside the cloaca, which is a common chamber for the digestive, urinary, and reproductive tracts. The papilla is a small, nipple-like organ located inside the cloaca that is used by male birds to deposit sperm inside the female's reproductive tract for insemination. Cowper's gland, seminal vesicle, and the male private part are not associated with bird reproduction.