Correct Answer: C

Rationale: The correct answer is that the client has been treated for breast cancer. Combination oral contraceptives containing estrogen and progestin are contraindicated for women with a history of certain conditions, such as thrombophlebitis, thromboembolic disorders, cerebrovascular disease, coronary artery disease, myocardial infarction, known or suspected breast cancer, known or suspected estrogen-dependent neoplasm, benign or malignant liver tumors, and undiagnosed abnormal genital bleeding. Although having type 2 diabetes mellitus, being treated for hypertension, or having hyperlipidemia are risk factors that require caution when using combination oral contraceptives, they are not absolute contraindications like a history of breast cancer.

Correct Answer: A

Rationale: Electrolytes are distributed unequally between intracellular and extracellular fluids. Sodium concentration is higher in extracellular fluid, while potassium concentration is higher in intracellular fluid. Therefore, the correct answer is 'There is a greater concentration of sodium in extracellular fluid and potassium in intracellular fluid.' Choices B, C, and D are incorrect because they do not accurately describe the typical distribution of sodium and potassium between intracellular and extracellular fluid.

Correct Answer: C

Rationale: The correct answer is 6 years old. At this age, children typically have the potential for 20/20 vision. This is considered the standard age for achieving optimal vision clarity. Choices A, B, and D are incorrect as they are not typically associated with the age at which children achieve 20/20 vision.

Correct Answer: D

Rationale: In diabetes insipidus, the pituitary releases too much antidiuretic hormone (ADH), causing the client to produce a large amount of dilute urine (decreased osmolarity) and leading to dehydration (elevated serum osmolarity). Therefore, the correct answer is decreased urine osmolarity and elevated serum osmolarity. Choice C, elevated urine osmolarity and decreased serum osmolarity, is incorrect for diabetes insipidus, as it is more characteristic of syndrome of inappropriate ADH (SIADH). Choices A and B, elevated urine osmolarity and elevated serum osmolarity, and decreased urine osmolarity and decreased serum osmolarity, respectively, are generally not seen in diabetes insipidus, as urine and serum osmolarity typically move in opposite directions in this condition.

Correct Answer: B

Rationale: Beta cells are responsible for secreting insulin. Insulin is produced by beta cells in the pancreas and plays a crucial role in regulating blood sugar levels. Alpha cells secrete glucagon, not insulin (Choice A). CD4 cells are a type of immune cell that helps coordinate the immune response (Choice C). Helper cells are a type of immune cell that aids in activating other immune cells (Choice D). Therefore, the correct answer is beta cells.