Final answer:
The Global War on Terrorism Service Medal can be worn by military personnel who have participated in or supported operations from 2001 onwards, following the terrorist attacks of September 11. This medal recognizes service in the War on Terror, commenced by the United States and allies to target Al-Qaeda and related militant groups.
Step-by-step explanation:
The Global War on Terrorism Service Medal is an accolade awarded to military personnel who have taken part in or supported operations related to the Global War on Terrorism. Initiated in response to the catastrophic terrorist attacks of September 11, 2001, which resulted in the tragic loss of nearly 3,000 lives, the United States and its allies commenced the War on Terror. This international mission, spearheaded primarily by the United States and the United Kingdom, aimed to dismantle Al-Qaeda and associated militant entities. The eligibility to wear the Global War on Terrorism Service Medal pertains to those who have been involved in specified operations from a certain year, continuing up to a presently undefined date. The correct answer to the query regarding the starting year for the eligibility of this medal is A) 2001.