Which document indicates the initiation of financial transactions?

The initiation of financial transactions is primarily documented through a transaction receipt. This receipt serves as a formal acknowledgment that a financial exchange has taken place. It includes crucial details such as the date, amount, type of transaction, and the parties involved, acting as a comprehensive record for both the purchaser and the seller.

In contrast, other options like a loan agreement and an insurance policy serve distinct purposes. A loan agreement outlines the terms of borrowing but does not document the immediate processing of a transaction; it is more about the conditions and obligations of the parties involved in lending. An insurance policy provides assurance against risks and outlines coverage but is not directly related to the initiation of financial transactions. Finally, an annual report summarizes a company's financial performance over a year, which is retrospective and does not document individual transactions as they occur.

Thus, the transaction receipt is the most accurate answer, as it directly reflects the initiation of a financial interaction at the moment it happens.