Which statement is used to select a default database?

Answer: Option A

This question asks about the command used to tell MySQL which database you want to work with. Think of it like choosing a specific folder on your computer to store and access files.

Here's how the options work:

Option A: USE - This is the correct answer! The USE statement tells MySQL which database you want to use for your queries. For example, USE my_database will make the database named "my_database" active.

Option B: CREATE - This is used to create a new database.

Option C: DROP - This is used to delete an existing database.

Option D: SCHEMA - This is a keyword used to refer to the structure of a database, but it doesn't directly select a default database.

Therefore, the correct answer is Option A: USE.