Final answer:
A pure service is an entirely intangible act or labor for which people pay, and among the options provided, the service by a transport agency best fits this description as it does not inherently include any tangible goods. The correct answer is option d.
Step-by-step explanation:
An example of a pure service is an economic product that involves no tangible goods, but rather an act or labor for which people are willing to pay. Comparing the options provided: a beautician typically provides a service that may include tangible products like creams or shampoos; an Internet cafe offers the service of internet access but often includes the use of their physical computers; a restaurant provides food which is a tangible good; and a transport agency provides the service of moving people or goods from one place to another.
Out of the options given, a service provided by a beautician, a service provided by an Internet cafe, and a service provided by a restaurant include tangible elements in the form of products used during the service or the end product itself.
Therefore, the most fitting example of a pure service, which involves no tangible good at all, is d. A service provided by a transport agency.