Final answer:
A customer is someone who pays for or uses a product or service, usually within an external or internal context. They have specific needs that design projects aim to meet and are considered stakeholders along with other interested parties who might not necessarily pay for the product.
Step-by-step explanation:
A customer is defined as a person or organization that pays for or uses a product or service. In the context of design projects, the purpose is typically to meet the needs of customers and stakeholders. A customer is someone who will utilize the designed object and who usually pays for the product. Stakeholders, on the other hand, include anyone who has an interest in the product, which can be a broader group than customers alone. While customers are also stakeholders, additional stakeholders could be government agencies, companies, and individuals who, while they might not purchase the product, still have a vested interest in it.
Therefore, the definition of a customer can be most closely associated with options A and B: An external paying customer (A), who purchases the product or service, or an internal customer (B), who might use a product or service within the same organization. However, option C, a non-paying external customer, does not align with the key element of paying for the service or product. Option D, anyone with whom you interact, is too broad and does not necessarily describe a customer in the business context.