The correct answer is: Mark the end of a batch of statements.

The Mark the end of a batch of statements option is correct because GO is a batch separator that client tools such as sqlcmd and SQL Server Management Studio recognize to indicate that the current set of Transact SQL statements should be sent to the server together. It is not a Transact SQL statement executed by the server and it simply tells the client to submit the current batch for execution.

The Mark the end of a batch of statements behavior also affects scope and statement ordering. Variables declared in one batch are not visible in the next batch and some statements must appear at the start of a batch so splitting with GO is often required in scripts.

Invoke a stored procedure to execute its logic is incorrect because stored procedures are invoked with EXEC or EXECUTE and not with GO. GO does not call or run a procedure.

Start a transaction that spans multiple commands is incorrect because transactions are started with BEGIN TRANSACTION and controlled with COMMIT or ROLLBACK. GO does not begin or commit a transaction and it is only a batch separator on the client side.

Convert several lines into a commented out block is incorrect because commenting is done with -- for single line comments or with /* and */ for block comments. GO does not turn lines into comments.

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