Correct Answer: C

Rationale: Whole milk should not be introduced before 12 months because it lacks the necessary nutrients, such as iron, that infants need for proper growth and development.

Correct Answer: B

Rationale: Heating formula in a plastic bottle in the microwave can cause uneven heating and release harmful chemicals from the plastic.

Correct Answer: C

Rationale: The correct answer is C. According to Erikson, the primary task of a preschool-aged child is to explore and assert control over their environment. This behavior is demonstrated by the child opening drawers, pulling out supplies, and examining them, showcasing curiosity and exploration. Choices A, B, and D do not align with the primary developmental task of a preschool-age child according to Erikson. Reading a book and singing a song are more passive activities, while roughhousing with the parent does not directly relate to exploration and asserting control over the environment.

Correct Answer: B

Rationale: Hepatitis B vaccination should start at birth, and any child or adolescent not vaccinated should complete the series. Adolescents should receive three doses if they were not previously vaccinated.

Correct Answer: A

Rationale: Letting an infant cry for prolonged periods can exacerbate colic and increase the infant's distress. It is better to respond promptly to soothe the baby. Other methods like swaddling, gentle massage, and keeping the infant upright can help relieve colic symptoms.