Final answer:
The position that requires the patient to lie flat on his or her back is 1) supine.
Step-by-step explanation:
When a patient is supine, they are lying face up with their back on a flat surface. This position is commonly used during medical examinations, such as physical assessments or certain surgical procedures.
In contrast, the position prone describes a face-down orientation, where the patient is lying on their stomach with their back facing up. Other positions mentioned in the question, such as Sims and Fowlers, do not involve the patient lying flat on their back. Therefore, the correct answer is option 1) Supine.