Correct Answer: B

Rationale: In laryngotracheobronchitis (croup), a child may become restless due to poor oxygenation. Increasing the oxygen concentration in the oxygen tent is crucial to improve oxygenation levels and manage symptoms effectively. Restraint is not appropriate in this situation, as it may cause distress and worsen the child's condition. Taking the child to the playroom is not indicated when the child requires oxygen therapy. While comforting the child is important, the priority in this scenario is to optimize oxygen delivery to improve respiratory distress.

Correct Answer: D

Rationale: The correct answer is 'negative association.' A negative association occurs when a person develops a dislike for a food due to a past negative experience, such as getting sick after eating it. In this case, the child's dislike of noodle soup is specifically linked to the negative experience of consuming it while sick with the flu. Choices A, B, and C are incorrect because the situation described does not relate to habit formation, social interactions, or emotional turmoil, but rather to a learned aversion based on a specific negative event.

Correct Answer: A

Rationale: The main purpose of Recommended Dietary Allowances (RDAs) is to provide guidelines for nutrient intakes that meet the needs of most healthy people. Choice B is incorrect because RDAs aim beyond just survival requirements. Choice C is incorrect because establishing maximum safe levels is the role of Tolerable Upper Intake Levels (ULs). Choice D is incorrect because preventing chronic diseases is more associated with Dietary Reference Intakes (DRIs) like Adequate Intakes (AIs) and Tolerable Upper Intake Levels (ULs). Therefore, the correct answer is A.

Correct Answer: B

Rationale: Rapid breathing is a common sign of a respiratory infection in infants. When infants have a respiratory infection, their breathing may become rapid as their body tries to get more oxygen. This symptom is often seen alongside cough and fever. Increased appetite (Choice A) is not typically associated with respiratory infections but can be seen in other conditions. Decreased urine output (Choice C) is more indicative of dehydration or kidney issues rather than a respiratory infection. Lethargy (Choice D) can be a symptom of various illnesses but is not as specific to respiratory infections as rapid breathing.

Correct Answer: C

Rationale: An essential nutrient is a substance that cannot be made in sufficient quantities by the body itself, so it must be obtained from the diet. Choice A is incorrect because essential nutrients are required in specific amounts, not necessarily large quantities. Choice B is incorrect as essential nutrients cannot be synthesized by the body at all. Choice D is incorrect because although essential nutrients may be used in the synthesis of other compounds, that is not the defining characteristic of an essential nutrient.