Correct Answer: C

Rationale: The correct answer is 22 gauge. A 22-gauge needle is recommended for school-age children, toddlers, and adolescents due to their muscle mass and tolerance. In infants, a smaller gauge (23-25) is preferred as their muscles are less developed and more sensitive. Choice A, 27 gauge, is too thin for an intramuscular injection in a 12-year-old boy. Choice B, 25 gauge, is more suitable for infants than for a 12-year-old. Choice D, 20 gauge, is too thick and not typically used for intramuscular injections in children.

Correct Answer: B

Rationale: The correct answer is B because pain in the left calf could indicate a potential neurovascular complication related to the casted extremity. It could suggest issues such as compartment syndrome or impaired circulation. Option A is not as concerning since not elevating the extremity may lead to swelling but is not an immediate concern. Option C indicates itching, which is common with casts and not as concerning as potential neurovascular issues. Option D, regarding arthritis in the wrists, is unrelated to the lower extremity issue being screened for.

Correct Answer: C

Rationale: Acinar cells are responsible for creating exocrine secretions, such as enzymes and digestive juices. Alpha cells are found in the pancreas and are responsible for producing glucagon, beta cells produce insulin, and plasma cells are a type of white blood cell involved in immune responses. Therefore, the correct answer is acinar cells, as they specifically produce exocrine secretions.

Correct Answer: B

Rationale: In a patient with COPD and CHF experiencing a sudden increase in total body weight, the priority is to check the intake and output on the patient's flow sheet to evaluate fluid balance. This assessment helps determine if the weight gain is due to fluid retention, which can exacerbate CHF. Contacting the physician may be necessary based on the intake and output findings. While encouraging ambulation is beneficial for circulation, it may not address the root cause of fluid retention. Checking vitals every 2 hours is important for monitoring stability but may not pinpoint the reason behind the weight gain.

Correct Answer: C

Rationale: H. pylori is the most common microorganism associated with gastritis, present in over 80% of cases. While syphilis, cytomegalovirus, and mycobacterium can also cause gastritis, they are much less prevalent compared to H. pylori. Therefore, the correct answer is H. pylori.