Correct Answer: A

Rationale: The correct answer is A: Loss of self-tolerance. This is because autoimmune diseases result from a breakdown in the immune system's ability to distinguish between self and non-self antigens, leading to the production of antibodies against self-antigens. When self-tolerance is lost, immune cells mistakenly target the body's own tissues, causing tissue damage and inflammation. Choice B (Failure of innate immunity) is incorrect because autoimmune diseases are primarily driven by adaptive immunity rather than innate immunity. Choice C (Defective T cell activation) is incorrect as T cells play a critical role in the immune response to self-antigens in autoimmune diseases. Choice D (Impaired phagocytosis) is incorrect as phagocytosis is a mechanism primarily involved in the removal of pathogens, not in the development of autoimmune diseases.

Correct Answer: C

Rationale: The correct answer is C: Secures clean ties before removing soiled ones. This is the priority action because securing clean ties prevents accidental dislodgement of the tracheostomy tube, ensuring the patient's airway remains patent. Cutting the dressing (A) or cleaning the incisions (B) can be important but not as critical as securing the tube. Using clean technique (D) is essential but not the priority in this situation.

Correct Answer: D

Rationale: The correct answer is D because informed consent should be obtained from both the participants and their parents to ensure full understanding and agreement from all parties involved. This is crucial when working with minors to protect their rights and ensure ethical standards are met. Choice A is incorrect as it excludes parental consent, which is necessary for minors. Choice B is also incorrect as it neglects the participants' direct involvement in consenting to participate. Choice C is incorrect because it only includes available relatives, which may not be legally authorized to provide consent on behalf of the participants.

Correct Answer: C

Rationale: The correct answer is C, to have a limited intake of sodium. Lithium can lead to increased sodium levels in the body, potentially causing toxicity. By limiting sodium intake, the patient can maintain a balance and prevent adverse effects. Choice A is incorrect as tyramine content is not directly related to lithium intake. Choice B is incorrect as fluid intake does not have a significant impact on lithium levels. Choice D is incorrect because an adequate intake of sodium can lead to worsening lithium toxicity.

Correct Answer: C

Rationale: Rationale: - ARDS is characterized by severe hypoxemia and respiratory distress. - Tachypnea is a hallmark sign of ARDS due to the body's compensatory mechanism to increase oxygenation. - Hypoxemia refractory to supplemental oxygen signifies the inability to improve oxygen levels despite intervention. - Choices A, B, and D do not align with typical manifestations of ARDS, as they do not directly reflect severe hypoxemia or respiratory distress.