Final answer:
While all the presented options involve some level of tangible product, the concept of a pure service applies to services that are intangible, where no physical product is involved in the transaction.
Step-by-step explanation:
The question 'Which of the following is an example of a pure service?' falls under the category of questions regarding business and economics, more specifically, the classification of goods and services. When evaluating the options provided, a pure service refers to a service that is entirely intangible, meaning there is no physical product involved in the transaction. With this definition, the answer would be one that represents a service free from goods. Ironically, all presented options (service provided by a restaurant, beautician, internet cafe, and transport agency) involve some level of tangible product. However, the question might be seeking which option is most dominantly a service, even if not purely intangible.