Which of the following is a requirement for all tour guides?

A city tour guide license is a specific requirement that ensures individuals have met the necessary standards to operate as a professional guide. This licensing typically involves knowledge of local history, culture, and regulations, which helps maintain the quality and safety of the tourism experience for visitors. Having a license also establishes credibility and trust with tourists, allowing them to feel secure in the information and services they are receiving during their tour.

The other options, while potentially useful or common practices in the industry, do not universally apply to all tour guides. Not every tour guide is required to wear a uniform, have prior tourism experience, or carry a first aid kit, as these can vary based on individual operator policies, the type of tours conducted, and local regulations. Thus, possessing a city tour guide license stands out as the foundational requirement for guiding in that specific area.