Final answer:
Selling costs include sales commissions, advertising, and sales salaries, which are expenses directly related to the selling process. Administrative salaries, however, are not categorized as selling costs. Hence, options B, C & D are correct answers.
Step-by-step explanation:
Selling costs include expenses directly related to the selling process of a company's goods or services. Among the options given, sales commissions, advertising, and sales salaries are considered to be selling costs. These are the costs incurred to generate revenue, and typically include items related to the sales personnel, marketing efforts, and distribution of the product or service.
On the other hand, administrative salaries are not considered selling costs but rather administrative or general expenses.
Hence, options B, C & D are correct answers.