Correct Option: D. Sales invoice and debit note Explanation of Why the Answer is Correct: Source Documents Defined: Source documents are the original records that contain the details of a transaction. They serve as the foundation for recording financial transactions in the accounting system. These documents provide evidence that a transaction occurred and include information such as the date, amount, parties involved, and nature of the transaction. Analysis of Option D: - Sales Invoice: This is a document issued by a seller to a buyer that outlines the products or services provided, the amount due, and the payment terms. It serves as proof of sale and is essential for both the seller's and buyer's accounting records. - Debit Note: This is a document issued by a buyer to a seller, indicating a return of goods or a request for a reduction in the amount owed. It serves as evidence of a transaction that affects the accounts payable and inventory. Both the sales invoice and debit note are primary documents that provide evidence of transactions, making them source documents. Why the Other Options Are Incorrect: Option A: Journal and Ledgers - Journal: While journals are used to record transactions, they are not source documents. Instead, they are secondary records that summarize the information from source documents. - Ledgers: Ledgers are used to categorize and summarize transactions recorded in journals. Like journals, they are not source documents but rather a compilation of data from source documents. Option B: Sales Invoice and Cash Book - Sales Invoice: Correctly identified as a source document. - Cash Book: This is a record that tracks cash transactions (both receipts and payments). While it is important for accounting, it is not a source document itself; it is a summary of transactions that have been recorded from source documents. Option C: Cash Book and Debit Note - Cash Book: As mentioned, it is not a source document but a record of cash transactions. - Debit Note: Correctly identified as a source document. However, since the cash book is not a source document, this option is incorrect. Summary of Key Points:

• Source Documents: Original records that provide evidence of transactions (e.g., sales invoices, debit notes).
• Sales Invoice: Proof of sale, detailing products/services and payment terms.
• Debit Note: Evidence of returns or adjustments in transactions.
• Journals and Ledgers: Secondary records that summarize information from source documents, not source documents themselves.

Revision Summary:

• Source documents are essential for accurate financial record-keeping.
• Sales invoices and debit notes are key examples of source documents.
• Journals and ledgers are not source documents; they summarize transactions.
• Understanding the role of each document type is crucial for effective accounting practices.