Final answer:
In a safety demonstration for life jacket usage, the inflation tube can be held in either hand, depending on what is most comfortable or practical for the individual.
Step-by-step explanation:
During a safety demonstration, specifically for the proper usage of a life jacket, the correct procedure is often demonstrated by the flight attendants or instructional videos.
When it comes to holding the inflation tube, the standard practice does not typically specify a particular hand that must be used. Therefore, the answer to the question, 'Which hand holds the inflation tube on the life jacket during the safety demo?' would be D) Either hand. This allows flexibility for the demonstrator or user, and may depend on what is most comfortable or practical in the situation.