Answer:
a. an invoice recording the details of a recent sale made by the company
Step-by-step explanation:
Information is obtained from an external source if its origin is outside the organization. It is information that was not obtained from a firm's internal documents or its employees. Newspapers, magazines, financial journals are some of the sources of external information to a firm.
An invoice is an internal document in an organization. It contains details of purchases and the related payments a firm expects to make. An invoice is addressed to the firm. It is an internal source of information as the business uses it to generate financial statements.