Final answer:
After immersing a patient's foot in a hot soak, the medical assistant should ask the patient how the temperature feels.
Step-by-step explanation:
After immersing a patient's foot in a hot soak, the medical assistant should ask the patient how the temperature feels. This is important to assess the patient's comfort and adjust the temperature if necessary.
Adding crushed ice (option A) is not recommended as it could cause further discomfort or injury to the patient. Increasing the temperature of the water (option B) would also not be appropriate as it could lead to burns or scalding. Instructing the patient to wiggle his/her toes (option C) is a general practice to improve blood circulation and comfort, but it does not address the temperature concern directly.