To create a database only if it doesn't already exist, which clause is used?

Answer: Option B

This question is about creating a database in MySQL. In MySQL, you can use the CREATE DATABASE command to create a new database.
But what if you want to make sure the database doesn't already exist before creating it? That's where the IF NOT EXISTS clause comes in.
Here's how it works:
* CREATE DATABASE IF NOT EXISTS database_name;
This command will only create the database if a database with the name database_name doesn't already exist.
So the correct answer is Option B: IF NOT EXISTS.
The other options are not valid SQL clauses for this purpose.