Correct Answer: C

Rationale: The correct answer is C, Interstitial. An ectopic pregnancy most commonly occurs in the interstitial portion of the fallopian tube. This is because the interstitial part is narrow and not suitable for the growing embryo, leading to implantation outside the uterus. Choices A, B, and D are incorrect because although ectopic pregnancies can occur in various locations, the interstitial portion of the fallopian tube is the most frequent site for such pregnancies.

Correct Answer: A

Rationale: Hysterosalpingo-contrast Sonography is a test used to check a woman's fallopian tubes with an X-ray and dye test called a hysterosalpingogram. This test is specifically designed to evaluate the patency of the fallopian tubes and the uterine cavity. Choices B, C, and D are incorrect as they do not align with the purpose of Hysterosalpingo-contrast Sonography.

Correct Answer: A

Rationale: Luteinizing hormone is responsible for maintaining the corpus luteum after ovulation. This is crucial for the production of progesterone, which helps prepare the endometrium for implantation and supports early pregnancy. Choices B, C, and D are incorrect: B is the function of follicle-stimulating hormone (FSH) which stimulates the growth of ovarian follicles, C is mainly regulated by prolactin, and D is primarily associated with estrogen and progesterone.

Correct Answer: C

Rationale: The luteal phase corresponds with the secretory phase. During the menstrual cycle, the luteal phase follows ovulation and is characterized by the development of the corpus luteum, secreting progesterone to prepare the endometrium for a potential pregnancy. The other choices, menstrual phase (A), follicular phase (B), and the repeated choice of menstrual phase (D) do not align with the luteal phase and its functions.

Correct Answer: B

Rationale: Culdocentesis is the correct procedure performed to assess the pelvic cavity, often used in the diagnosis of Pelvic Inflammatory Disease. Paracentesis involves the aspiration of fluid from the abdominal cavity, not typically done for PID. Hysterectomy is the surgical removal of the uterus and is not a diagnostic investigation for PID. Douching is a hygiene practice and not a diagnostic procedure for PID.