Correct Answer: C

Rationale: A murmur is produced by turbulent blood flow within the heart or major arteries, resulting in audible vibrations.

Correct Answer: D

Rationale: Using a cotton swab, allowing the child to observe, and demonstrating on someone else are effective ways to encourage a preschooler to open their mouth for examination.

Correct Answer: C

Rationale: The oral mucosa and conjunctivae are the best places to observe petechiae in dark-skinned individuals because these areas have less pigmentation.

Correct Answer: D

Rationale: Increased screen time is associated with unhealthy habits, such as poor sleep and snacking, which contribute to obesity, but it does not necessarily improve nutrition knowledge.

Correct Answer: C

Rationale: The correct answer is C. Falling when bending over to touch toes could indicate a developmental delay or a balance issue that may need further assessment. Choices A, B, and D are typical developmental milestones for a 3-year-old child. Pedaling a tricycle without assistance, unscrewing a bolt on a toy, and building a tower of 10 cubes are all age-appropriate activities for a child of this age.