Which of the Following Is the Key Reason for Attaching

Which of the following is the key reason for attaching a letter of transmittal to a report?

A) To conform to standard business practice.
B) To address the report to a reader, personalising it in the process, and calling attention to specific details relevant to that reader.
C) To ask people to read the report.
D) To ensure that readers know who wrote the report.
E) To attach an invoice and ensure its payment.