Final answer:
Services are unique and tailored to individual needs, exhibiting heterogeneity, and can be excludable when only those who pay may access them, relating to the concept of comparative advantage in cost-effective production.
Step-by-step explanation:
Because a service is individually produced and is virtually unique, the service is said to have heterogeneity as each service can be tailored to an individual's specific needs and requirements. This is in contrast to goods, which are tangible and can be mass-produced with uniformity. Services are not always excludable, meaning not everyone may have access to them; often, only those who can pay for them may use them. These characteristics of services highlight their uniqueness and value proposition, which is intrinsically linked to the concept of comparative advantage. Comparative advantage occurs when one entity can produce a good or service in a more cost-effective manner than another entity. In the context of international trade, it's when one country can create a particular good or service more efficiently compared to another country.