A progestin and an estrogen are combined in oral contraceptive pill because:

Correct Answer: C

Rationale: The correct answer is C because progestin and estrogen work together to suppress ovulation by inhibiting the release of gonadotropins. Progestin thickens cervical mucus, making it hostile to sperm, while estrogen stabilizes the endometrium. Choices A and B are incorrect because the hormones don't block each other's side effects. Choice D is incorrect because it oversimplifies the mechanism of action.

Correct Answer: C

Rationale: Step-by-step rationale: 1. Mifepristone is an antiprogestin as it competitively inhibits progesterone receptors. 2. Gemeprost is a prostaglandin analog, not an antiprogestin. 3. Megestrol is a progestin, promoting progesterone-like effects. 4. Tamoxifen is a selective estrogen receptor modulator, not an antiprogestin. Summary: A, B, and D are incorrect as they do not possess antiprogestin properties. Mifepristone is the correct choice due to its specific mechanism of action as an antiprogestin.

Correct Answer: A

Rationale: The correct answer is A: Rise in body temperature. Progesterone does not directly cause a rise in body temperature; this is primarily regulated by the hypothalamus. Progesterone's main actions include endometrial proliferation, proliferation of acini in the mammary gland, and suppression of cell-mediated immunity. Endometrial proliferation prepares the uterus for implantation, mammary gland proliferation prepares for lactation, and suppression of immunity prevents rejection of the fetus during pregnancy. Other choices are incorrect because they are well-documented actions of progesterone.

Correct Answer: D

Rationale: The correct answer is D: Improved lipid profile. Tamoxifen citrate therapy does not have a direct effect on improving lipid profile. A: Reduction in recurrence rate of breast cancer - Tamoxifen is used to reduce the risk of breast cancer recurrence. B: Improved bone mass - Tamoxifen can help maintain or improve bone density. C: Suppression of menopausal hot flushes - Tamoxifen can help reduce menopausal symptoms like hot flushes. In summary, choices A, B, and C are benefits of tamoxifen therapy, while choice D is not supported by evidence.

Correct Answer: D

Rationale: The correct answer is D (2-4 weeks) because rotating injection sites every 2-4 weeks helps prevent lipodystrophy and tissue damage. Insulin absorption may vary with frequent rotation, affecting glucose control. Choice A is too frequent and may lead to overuse of specific sites, increasing the risk of complications. Choice B is also too frequent and doesn't allow enough time for the tissue to recover. Choice C is too long, increasing the likelihood of uneven insulin absorption and potential complications. Rotation every 2-4 weeks strikes a balance between preventing damage and ensuring consistent insulin absorption.