Which clause specifies periodic execution at fixed intervals?

Answer: Option A

This question is about how to set up tasks in MySQL that run automatically at specific times.
The options are different ways to describe the timing of these tasks:
Option A: EVERY - This is the correct answer! It's used to define tasks that happen repeatedly at fixed intervals. For example, "EVERY 10 minutes" or "EVERY hour".
Option B: ALL - This is not used for specifying intervals in MySQL.
Option C: AT - This is used for scheduling tasks to run at a specific point in time, like "AT 10:00 AM".
Option D: ALTERNATE - This is not used for scheduling tasks in MySQL.
So, if you want a task to run regularly, you'd use the "EVERY" clause to set the time between executions.