Which statement about nitrous oxide is true?

Which statement about nitrous oxide is true?

An 8-month-old girl is brought to the emergency department by her parents because she has been “acting funny.” They say she has been weaker than normal. She is afebrile but appears lethargic. While talking with the parents, you discover that they sometimes give her honey to calm her down and gave her a spoonful yesterday. What is the mechanism of the toxin likely causing her symptoms?

A 58-year-old man with cardiac dysfunction is placed on propranolol. Over the ensuing days, he develops worsening pedal edema, and review of his serum electrolyte reveals a serum sodium of 151 mEq/L. What is the most appropriate treatment for this patient?

A 40-year-old man with chronic anxiety and alcohol abuse has difficulty getting to sleep. He has no other medical problems. Physical examination of the heart, lungs, and abdomen are within normal limits. Which of the following is the best agent to help this patient get to sleep?

A 19-year-old college student has come to the conclusion that smoking one cigarette per day may help him excel in his classes. Note: This behavior is not endorsed by the American Medical Association. The student's belief in having one cigarette per day may actually improve which of the following performance areas?