Correct Answer: B

Rationale: The correct answer is B: 'It decreases bone resorption and increases bone density.' Raloxifene, as a selective estrogen receptor modulator (SERM), works by reducing bone resorption (breakdown) and maintaining or increasing bone density. This mechanism helps in preventing further bone loss and can even increase bone mass. Choices A, C, and D are incorrect. Raloxifene does not stimulate the formation of new bone (choice A), increase calcium absorption in the intestines (choice C), or increase the excretion of calcium through the kidneys (choice D).

Correct Answer: C

Rationale: Women with a history of breast cancer should avoid hormone replacement therapy due to the increased risk of cancer recurrence.

Correct Answer: D

Rationale: The correct answer is IgM. IgM is the first immunoglobulin to appear in response to a new antigen. It is produced initially during the primary immune response. IgA is mainly found in mucosal areas and secretions. IgG is produced in a secondary immune response and is the most abundant immunoglobulin in the bloodstream. IgE is involved in allergic reactions and parasitic infections, not the initial response to a new antigen.

Correct Answer: B

Rationale: The correct answer is B: 'vigilant adherence to the drug regimen.' When initiating oral contraceptive therapy, the success of preventing pregnancy relies heavily on the patient's commitment to following the prescribed regimen consistently. Compliance with taking the oral contraceptives as directed is crucial for their effectiveness. Choice A, 'current health status,' is not the primary factor for successful prevention of pregnancy with oral contraceptives. Choice C, 'knowledge of sexual health,' while important, is not the primary determinant of contraceptive efficacy. Choice D, 'risk factors for adverse effects,' though relevant for monitoring and managing side effects, is not the primary focus for ensuring contraceptive success.

Correct Answer: C

Rationale: The correct answer is C. Oral contraceptives can be less effective when taken with certain antibiotics as they may interfere with the effectiveness of the contraceptive. It is important for patients to be aware of this interaction to consider additional contraceptive methods during antibiotic therapy. Choices A and B are incorrect as no contraceptive method is 100% effective, and oral contraceptives typically require a period of time to reach full effectiveness. Choice D is incorrect as taking oral contraceptives with food does not significantly impact their effectiveness.