Final answer:
Costs like office rent, office staff, and insurances in the building business are classified as indirect costs, which are necessary for the overall operation of the business but not tied to the production of a specific product.
Step-by-step explanation:
Costs related to the business of being a builder such as office rent, office staff, and insurances are best described as indirect costs. These are costs that are not directly tied to the production of a specific product or service but are necessary for the general functioning of the business. Examples of indirect costs include rent for office space, wages for office staff, and various forms of insurance. These costs are in contrast to direct costs which are directly attributable to the production of a product, such as raw materials and labor on the construction site. Understanding the difference between these types of costs is essential for budgeting and financial management in any business.