Correct Answer: A

Rationale: Duchenne muscular dystrophy is an X-linked recessive disorder caused by mutations in the DMD gene on the X chromosome. This disorder primarily affects males because they have one X chromosome, inherited from their mothers, who may be carriers of the mutated gene. Females have two X chromosomes, providing a protective effect as the normal gene on one X chromosome can compensate for the mutated gene on the other. Therefore, the nurse should explain to the parents that Duchenne muscular dystrophy is an inherited X-linked recessive disorder, which is why their son has the disease and why there is a risk of passing it on to future sons.

Correct Answer: A

Rationale: Duchenne muscular dystrophy is an X-linked recessive disorder caused by mutations in the DMD gene on the X chromosome. This disorder primarily affects males because they have one X chromosome, inherited from their mothers, who may be carriers of the mutated gene. Females have two X chromosomes, providing a protective effect as the normal gene on one X chromosome can compensate for the mutated gene on the other. Therefore, the nurse should explain to the parents that Duchenne muscular dystrophy is an inherited X-linked recessive disorder, which is why their son has the disease and why there is a risk of passing it on to future sons.

Correct Answer: B

Rationale: For individuals with celiac disease, a strict gluten-free diet is essential for managing the condition. Foods containing wheat, barley, and rye must be completely avoided to prevent adverse reactions and damage to the intestines. This dietary restriction is crucial to ensure the child's health and well-being in managing celiac disease effectively.

Correct Answer: A

Rationale: The first step in developing a behavior modification program for an aggressive child is to determine what activities, foods, and toys the child enjoys. By understanding the child's preferences, the nurse can tailor the program to be more engaging and effective, increasing the likelihood of success in modifying the aggressive behavior.

Correct Answer: D

Rationale: When a baby looks for a hidden object, it demonstrates the development of object permanence. This milestone is significant as it signifies the baby's understanding that objects continue to exist even when they are not visible. It is a crucial aspect of cognitive development in infancy.