Correct Answer: B

Rationale: Popcorn is a high-fiber food that can help manage chronic constipation in children. Other options like white rice and ripe bananas are low in fiber and less effective for treating constipation.

Correct Answer: A

Rationale: The primary reason for correcting cryptorchidism through surgery is to prevent damage to the undescended testicle, which can lead to infertility and increase the risk of testicular cancer. Prevention of UTIs and prostate cancer are not the primary concerns in this context.

Correct Answer: B

Rationale: If the mother is HBsAg negative, it is recommended that the child receives the first dose of the hepatitis B vaccine at birth before discharge from the hospital. This is to provide early protection against the hepatitis B virus. The second dose of the vaccine is typically given at the first well-child visit, and the third dose is usually administered at a later date. The Advisory Committee on Immunization Practices of the Centers for Disease Control and Prevention and the Committee on Infectious Diseases of the American Academy of Pediatrics govern the recommendations for immunization, including the hepatitis B virus vaccine. Choice A is incorrect as the first dose should ideally be given at birth. Choice C is incorrect as waiting until 6 months of age may leave the child vulnerable to infection during the early months of life. Choice D is incorrect as the hepatitis B vaccine is recommended for all newborns, especially if the mother is HBsAg negative, to prevent transmission of the virus.

Correct Answer: A

Rationale: Stool pH testing is used to screen for carbohydrate malabsorption. A low pH indicates the presence of unabsorbed carbohydrates, which are fermented by bacteria, leading to acidic stool.

Correct Answer: B

Rationale: Phimosis is the condition where the foreskin cannot be fully retracted over the glans penis due to a narrowing of the preputial opening. Chordee, epispadias, and hypospadias are different conditions involving the penis's structure.