Final answer:
The female sexual response begins with the excitement phase during which the reproductive organs become engorged with blood and the vestibular glands produce mucus.
Step-by-step explanation:
The female sexual response initiates with the excitement phase, during which the reproductive organs experience an increase in blood flow and the vestibular glands produce mucus. This phase involves vasodilation leading to vasocongestion in the erectile tissues of the nipples, labia, and vagina, resulting in their enlargement and engorgement with blood. Moreover, the vestibular glands secrete mucus to provide lubrication for the vagina, facilitating comfortable intercourse.