Which of the following are parts to know on a bull's reproductive tract?

The parts of a bull's reproductive tract that are crucial to understand include the testes, scrotum, and sigmoid flexure. The testes are responsible for producing sperm and hormones crucial for reproduction. The scrotum serves as a protective and thermoregulatory structure that houses the testes, ensuring that they remain at optimal temperatures for sperm production. The sigmoid flexure is a key feature of the male bovine anatomy, allowing for the extension and retraction of the penis, which is vital during mating. Knowing these components is essential for understanding male reproductive physiology and function in cattle.

In contrast, the other options focus on female reproductive anatomy, which does not pertain to the question about a bull's reproductive system. The ovaries, uterus, cervix, vagina, fallopian tubes, and vulva are all parts of the female reproductive tract and are therefore not relevant to understanding the male bull's anatomy.