None of the job titles listed (apparel graphic designer, logo designer, multimedia designer, publication designer) typically include the responsibility of being a brand ambassador. Brand ambassadors are usually roles focused on representing and promoting a brand, which is not a core function of the listed design positions. However, roles like a Marketing Coordinator or Brand Manager would more commonly involve brand ambassador responsibilities.
If you need to choose from the provided options, it would be best to select the one that comes closest to brand representation in a marketing context, if available. But with the given choices, none directly relate to being a brand ambassador.