Final answer:
To assess a patient's affect during a mental status examination, the nurse should ask, "How do you feel today?" as it directly targets the patient's emotional condition.
Step-by-step explanation:
The nurse wishes to assess a patient's affect during a mental status examination. Affect refers to the outward expression of a person's internal emotional state. Therefore, to evaluate a patient's affect, the most appropriate question would be: "How do you feel today?" This question specifically targets the patient's emotional condition and is likely to elicit a response that reflects their current affect. Questions about repeating words, the effects of medication on physical pain, or the impact of pain on the ability to dress do not directly assess effect and are more associated with cognitive function, pain management, and physical capability, respectively.