Correct Answer: D

Rationale: The correct answer is D: 'Before meals'. Chest physiotherapy should be performed before meals to reduce the risk of vomiting and to ensure that the airways are clear for effective nutrition. Choices A, B, and C are incorrect because chest physiotherapy is ideally done before meals to optimize its benefits and avoid complications associated with timing.

Correct Answer: D

Rationale: The prognosis for children with MCNS is closely related to their response to steroid therapy. A favorable response to steroids usually indicates a better prognosis, while poor response may require alternative treatments and can indicate a more complicated disease course.

Correct Answer: A

Rationale: When assessing a child with chronic renal failure, the nurse would expect to find uremic frost as a clinical manifestation. Uremic frost, a white powdery deposit of urea on the skin, occurs in severe cases of chronic renal failure due to the accumulation of urea and other waste products in the blood. Hypotension and massive hematuria are less common in chronic renal failure, while severe metabolic acidosis is typically mild to moderate and not a prominent clinical manifestation.

Correct Answer: C

Rationale: Vegetables, particularly pureed ones, are often recommended as a first solid food for infants because they are easy to digest and less likely to cause allergies. Fruits can be introduced later due to their natural sweetness, while eggs and meat are typically introduced after fruits and vegetables as they may pose a higher risk of allergies.

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.