When teaching a class about trisomy 21, the instructor would identify the cause of this disorder as:

Correct Answer: A

Rationale: Trisomy 21, also known as Down syndrome, is caused by nondisjunction, which is an error in cell division that leads to the presence of an extra chromosome 21. This additional chromosome alters the normal genetic makeup, resulting in the characteristics associated with Down syndrome. Therefore, the correct answer is nondisjunction (Choice A). Choices B, C, and D are incorrect because Trisomy 21 is not caused by X-linked recessive inheritance, genomic imprinting, or autosomal dominant inheritance. Understanding the specific genetic mechanism involved in Trisomy 21 is crucial for grasping the basis of this chromosomal disorder.

Correct Answer: B

Rationale: When parents of a toddler request to be present during a procedure, it is crucial to conduct an individual assessment of the parents. This assessment helps healthcare professionals understand the parents' ability to cope with the procedure, provide support to their child, and ensure a safe and comfortable environment for all involved. Choice A, the type of procedure to be performed, while important, is not the most critical factor in this scenario. Choice C, whether the toddler wants the parents present, is significant but secondary to assessing the parents themselves. Choice D, probable reaction to the toddler's response to pain, is important but focuses more on the child's reaction rather than the parents' capacity to provide appropriate support.

Correct Answer: B

Rationale: The correct answer is B: 'Toddlers are learning to assert independence, and this behavior is expected at this age.' At 18 months old, toddlers are in the stage of developing autonomy and testing boundaries. It is normal for them to exhibit behaviors such as temper tantrums and defiance as they explore their independence. Choice A is incorrect as discipline at this age is more about setting limits and providing guidance rather than preventing antisocial behaviors. Choice C is inappropriate as leaving a toddler alone in a crib after explaining unacceptable behavior is not a recommended approach for managing toddler behavior. Choice D is incorrect as the described behavior is typical of toddlers asserting independence, not related to the initiative stage of development. The best response involves acknowledging the child's developmental stage and understanding that these behaviors are part of their normal growth and development.

Correct Answer: D

Rationale: Macaroni and cheese and Cheerios are appropriate choices for a 30-month-old toddler on a regular diet as they provide a balance of carbohydrates and protein. Option A, hamburger with bun and grapes, may be difficult for a toddler to chew, and grapes pose a choking hazard. Option B, chicken fingers and french fries, are high in unhealthy fats and sodium. Option C, hot dog with bun and potato chips, are processed foods high in salt and unhealthy fats, not ideal for a toddler's diet.

Correct Answer: D

Rationale: The most crucial factor in successful toilet training is the parents' commitment to consistently work with their child. While parents' attitude and willingness are important, the key is their dedication to the process. The child's motivation and ability are also significant but rely heavily on parental guidance and support. Therefore, the correct choice is the parents' commitment to work on toilet training.