Which statement is used for updating existing information in the table?

Answer: Option A

This question is asking about the SQL command used to change data within an existing table. Let's break down the options:
Option A: UPDATE
This is the correct answer! The UPDATE statement is specifically designed for modifying data in a table. It allows you to change values in existing rows based on certain conditions.
Option B: WHERE
WHERE is not a command but a clause used within other statements, like UPDATE. It specifies which rows to affect when you use UPDATE.
Option C: MODIFY
MODIFY is used to change the structure of a table, such as altering column definitions (data type, size, etc.)
Option D: ALTER
Similar to MODIFY, ALTER is used for making structural changes to a table.
In summary, UPDATE is the statement used for changing the data in a table, while the others deal with table structure or conditions within statements.