Correct Answer: C

Rationale: Frequent spitting up is indeed a common symptom of gastroesophageal reflux in infants. It is caused by the backward flow of stomach contents into the esophagus, leading to infants regurgitating milk or formula shortly after feeding. Projectile vomiting (choice A) is more commonly associated with conditions like pyloric stenosis rather than gastroesophageal reflux. Bilious vomiting (choice B) often indicates an obstruction in the gastrointestinal tract. Diarrhea (choice D) is not typically a primary symptom of gastroesophageal reflux in infants.

Correct Answer: A

Rationale: The correct answer is A: Reduce proteinuria. In nephrotic syndrome, the primary treatment goal is to reduce proteinuria to prevent further kidney damage. Lowering blood pressure (choice B) is important in managing some types of kidney disease but is not the primary treatment goal in nephrotic syndrome. Increasing urine output (choice C) and preventing infections (choice D) are important aspects of supportive care but are not the primary treatment goal for nephrotic syndrome.

Correct Answer: B

Rationale: Rectal bleeding is more commonly associated with ulcerative colitis (UC) than with Crohn disease (CD). While both conditions can cause abdominal pain and growth issues, bleeding is a hallmark of UC due to its superficial mucosal inflammation. Perianal lesions are more characteristic of CD, and growth retardation is typically not a direct clinical manifestation of either CD or UC.

Correct Answer: A

Rationale: The correct answer is A, Hepatitis B. The Hepatitis B vaccine is usually given at birth to protect against hepatitis B, a virus that can lead to chronic liver disease and liver cancer. This vaccination is crucial for newborns, especially those born to mothers who are carriers of hepatitis B. Choices B, C, and D are incorrect because DTaP (B), MMR (C), and Varicella (D) vaccines are not typically administered at birth. DTaP is given in a series starting at 2 months, MMR is usually given around 12-15 months, and Varicella is given between 12-15 months of age.

Correct Answer: B

Rationale: Melena indicates bleeding from the upper GI tract. The black, tarry appearance of the stool results from the partial digestion of blood as it passes through the intestines, typically originating from sources like the stomach or duodenum. Lower GI bleeding usually presents as bright red blood in the stool, originating from sources like the colon or rectum. Choices A, C, and D are incorrect because melena specifically points to upper GI bleeding rather than issues in the perianal/rectal area, lower GI tract, or hemorrhoids/anal fissures.