A 50-year-old man with overactive bladder is started on oxybutynin 5 mg twice daily for urge incontinence. Two weeks later, he presents to the emergency department with constipation, urinary retention, and malaise. Vital signs are: temperature 38.5°C, heart rate 108 bpm, blood pressure 142/88 mmHg, respiratory rate 18/min, SpO2 98% on room air. Physical examination reveals warm, dry skin with absent diaphoresis, dilated pupils, and a palpably distended bladder. Mental status is clear. Laboratory studies show normal electrolytes, normal creatinine, and normal CBC. The patient denies fever, dysuria, or signs of infection prior to medication initiation. Which of the following best explains the constellation of findings in this patient?

1. A)Inhibition of nicotinic receptors at parasympathetic ganglia, blocking all parasympathetic outflow
2. B)Activation of central sympathetic pathways leading to systemic vasoconstriction and hyperthermia
3. C)Blockade of muscarinic M3 receptors in the bladder, colon, and eccrine sweat glands, combined with antimuscarinic effects on temperature regulationGABARITO
4. D)Competitive antagonism of acetylcholine at M1 receptors in the basal ganglia causing delirium
5. E)Direct inhibition of sweat gland function via α-adrenergic blockade and secondary thermoregulatory dysfunction