Which type of record summarizes all the transactions related to a single item in the accounting equation?

An account is a record that summarizes all the transactions related to a single item in the accounting equation. This means that for any given item – whether it's an asset, liability, equity, revenue, or expense – all the financial transactions that affect that item are recorded in its respective account.

For example, if you consider the “Cash” account, every transaction that involves cash inflows (like sales or receipts) and outflows (like expenses or payments) would be recorded in this account, allowing for a clear view of the cash position of the entity over time.

In contrast, journals and special journals are used for recording transactions in chronological order rather than summarizing individual item transactions. A source document, such as an invoice or receipt, provides evidence of a transaction but does not summarize the transaction flow for a specific item within the accounting system. Therefore, the concept of an account as a comprehensive record makes it the correct answer in this context.