Final answer:
During the admission process, the medical assistant should document the patient's concerns on the medical record.
Step-by-step explanation:
During the admission process, the medical assistant should take the action of documenting the patient's concerns on the medical record. This is important for keeping a comprehensive record of the patient's chief complaint and will assist the healthcare team in providing appropriate care. Other actions listed such as providing advice about temporary relief measures, reassuring the patient, and evaluating the relevance of the patient's concern may also be important, but documenting the patient's concerns on the medical record should be prioritized.