Correct Answer: B

Rationale: The most important nursing intervention during the first 48 hours for a client with anorexia nervosa is monitoring vital signs and electrolytes (B) to assess for life-threatening complications. This helps in early detection of any physiological imbalances that could lead to serious consequences. Providing high-calorie, high-protein meals (A) is important for nutritional rehabilitation but comes after ensuring the client's physical stability. Encouraging the client to talk about feelings (C) and observing for signs of purging (D) are relevant aspects of care but are not as critical as monitoring vital signs and electrolytes in the initial phase of treatment.

Correct Answer: A

Rationale: Determining if the client has access to a weapon is critical for immediate safety and to prevent potential harm.

Correct Answer: D

Rationale: The priority is to manage the client's medication adherence to prevent escalation of manic behavior. Inflated self-esteem is the highest priority as it indicates the client's potential for harmful behaviors due to lack of medication compliance. While excessive work activity and decreased need for sleep are characteristics of mania, they are not as immediately concerning as the risk of harm related to inflated self-esteem.

Correct Answer: B

Rationale: The correct answer is B: Projection. In this scenario, the client is projecting his own feelings of anger and selfishness onto his roommate. Projection is a defense mechanism where individuals attribute their own unacceptable thoughts, feelings, and motives to another person. Choices A, C, and D are incorrect. Denial is refusing to acknowledge an aspect of reality or experience. Rationalization is providing logical-sounding reasons to justify unacceptable behaviors or feelings. Splitting is seeing individuals as all good or all bad, with no middle ground.

Correct Answer: C

Rationale: The correct answer is C. PET scans are primarily used to detect and observe the metabolic activity in various parts of the brain. This helps in diagnosing conditions related to brain function, such as tumors, brain disorders, and overall brain activity. Choices A, B, and D are incorrect because PET scans focus on metabolic activity and functions in the brain rather than solely indicating the presence of tumors, outlining brain structures, or showing biochemical levels of neurotransmitters.