Correct Answer: D

Rationale: The correct answer is D because at 9 months, infants become more mobile, increasing the risk of choking hazards from small objects left on the floor. Cautioning about putting the infant in a walker (Choice A) is not as crucial at this age as warning about choking hazards. While advising how to create a toddler-safe home (Choice B) is essential, the most critical concern at 9 months is small objects. Instructing on safety procedures during baths (Choice C) is important but does not address the immediate risk of choking hazards associated with small objects.

Correct Answer: B

Rationale: At 10 months, children are beginning to understand simple commands like "no." It is important for parents to reinforce this understanding consistently to help the child learn about boundaries and safety.

Correct Answer: A

Rationale: The Advisory Committee on Immunization Practices (ACIP) of the Centers for Disease Control and Prevention (CDC) and American College of Obstetricians and Gynecologists recommend that pregnant adolescents and women without protection against pertussis should receive the Tdap vaccine ideally between 27 and 36 weeks of gestation or postpartum before discharge from the hospital. This timeframe allows for the development of antibodies in the mother to protect her and provide passive immunity to the infant. Administering the vaccine during the first trimester (Choice D) is not recommended as the optimal time is between 27 and 36 weeks. Choice B, during the first prenatal visit, is too early for optimal protection, and Choice C, 24 hours prior to delivery, does not provide enough time for the vaccine to be effective before birth.

Correct Answer: C

Rationale: Most infants can sit steadily without support by 8 months, indicating advanced gross motor skill development.

Correct Answer: C

Rationale: The correct answer is C: 'Abstract thinking.' According to Piaget's theory of cognitive development, adolescents, typically around the age of 12 and older, enter the formal operational stage where they can think abstractly and reason about hypothetical situations. When discussing complex topics like STIs with a 17-year-old student, it is essential to base the teaching plan on abstract thinking. Choice A, 'Sensorimotor reactions,' is incorrect as it pertains to the earliest stage in Piaget's theory (birth to 2 years old) focusing on sensory experiences and physical interactions. Choice B, 'Limited cause and effect understanding,' does not align with the cognitive abilities of a 17-year-old who is capable of more advanced thinking. Choice D, 'Concrete thinking,' is also incorrect as it refers to the stage before formal operations, where individuals think more concretely and struggle with abstract concepts.