Correct Answer: B

Rationale: Postinfectious glomerulonephritis is typically caused by immune complex deposition in the glomeruli following a streptococcal infection. This immune response leads to inflammation and impaired kidney function.

Correct Answer: D

Rationale: Infrequent voiding can lead to urinary stasis, which increases the risk of urinary tract infections by allowing bacteria to multiply in the bladder. Encouraging regular voiding and proper hydration can help prevent UTIs. Choices A, B, and C are incorrect. Excessive intake of carbonated beverages may irritate the bladder but is not a direct cause of UTIs. Insufficient water intake can concentrate urine but does not necessarily lead to infections. A voiding pattern of 5-6 times a day is within the normal range and is not associated with increased UTI risk.

Correct Answer: D

Rationale: The correct answer is D. Replacing carpet with hard flooring helps to reduce allergens and asthma triggers in the child's environment. Choice A is incorrect as having a dog in the child's room can worsen asthma symptoms due to pet dander. Choice B is incorrect because keeping plants in the child's room can increase mold spores and allergens. Choice C is incorrect as using a fireplace can introduce smoke and other irritants into the air, worsening asthma symptoms.

Correct Answer: B

Rationale: Toilet training should begin when the child has sufficient bladder capacity and control, which may be delayed in children who have undergone surgical repairs for conditions like bladder exstrophy. Premature training can lead to frustration and setbacks.

Correct Answer: B

Rationale: A sunken fontanel is a classic sign of dehydration in infants, indicating a fluid volume deficit. In dehydration, the fontanel sinks due to decreased fluid volume in the body. Increased blood pressure (Choice A) is not typically associated with dehydration in infants. Decreased pulse rate (Choice C) is not a common finding in fluid volume deficit, as the body tries to increase the heart rate to compensate for decreased volume. Low urine specific gravity (Choice D) may be seen in dehydration, but it is not as specific or as easily observable as a sunken fontanel.