A client at the mental health center reports difficulty concentrating at work, feeling very tired during the day, and sleeping 4 to 5 hours at night. To further assess for depression, which question is most important for the nurse to ask?

A. Inquiring about recent stresses is relevant but may not specifically address the emotional state associated with depression. B. Asking about food preferences is important for a comprehensive assessment but may not be the most direct question for assessing depression. C. Inquiring about whether the client often feels sad is crucial for assessing the emotional aspect of depression. D. While changes in sleep patterns are significant, the question about feeling sad directly addresses the emotional component of depression, which is important for a comprehensive assessment.