The correct answer is: A. Debtor.
A debtor is a person or entity that owes money to another person or entity. In the context of a business, a debtor is a customer who has not yet paid for goods or services that they have received from the business.
A creditor is a person or entity to whom money is owed. In the context of a business, a creditor is a supplier who has not yet been paid for goods or services that they have provided to the business.
An investor is a person or entity that provides money to a business in exchange for a share of ownership in the business.
A supplier is a person or entity that provides goods or services to a business.
In conclusion, a person who owes money to the business is a debtor.