Final answer:
The best control for voluntary motion is careful explanation, which helps patients understand the importance of staying still for medical procedures. Other methods include short exposure time and in rare cases, physical restraint.
Step-by-step explanation:
The best way to control voluntary motion, particularly in medical or imaging contexts, is through careful explanation. For instance, when conducting medical imaging like X-rays or MRIs, explaining the procedure and the importance of staying still can help patients cooperate and minimize movement. Sometimes other methods might be employed depending on the situation, such as short exposure time to reduce the chance for motion, or in rare cases, physical restraint may be necessary if a patient is unable to control their movements. However, immobilization techniques such as casts or braces are typically used for involuntary motion control due to injury, not for voluntary motion during procedures.