Explanation:

- Option 1: Operating expenses. This is correct. Operating expenses refer to the main ongoing costs incurred in the day-to-day running of a business, such as rent, utilities, and salaries.

- Option 2: Non-administration expense. This is not a standard term for describing the main operational costs of a business.

- Option 3: Selling expenses. These are a subset of operating expenses, specifically related to the promotion and distribution of products, but not the entirety of main operation expenses.

- Option 4: Administration expense. These are also part of operating expenses but refer specifically to expenses related to the general administration of the business.

Correct Answer: Option 1 (Operating expenses)