The file created by the server to store the database attributes is . . . . . . . .

This question is asking about a special file that MySQL uses to store information about your database. Think of it like a list of important details about the database.
Let's look at the options:
Option A: db.otp - This doesn't sound like a file used by databases.
Option B: dp.zip - This might be a compressed file, but not a file used by MySQL to store database information.
Option C: db.opt - This looks like a file related to a database! It's a common name for files that hold database settings.
Option D: db.cls - This doesn't seem like a file associated with databases.
So, the most likely answer is Option C: db.opt.
Remember, the exact name might vary depending on your specific MySQL setup, but the idea is that the database attributes (like table names, column types, etc.) are stored in a file.