Answer: i mean... ya open the door to let your parents in... but if you're one moody teen and don't feel like doing that, YOU STILL OPEN YOUR DOOR TO GET TO THE FRIDGE. THEN, YOU OPEN THE FRIDGE.
Explanation: whys the knock sudden? what if i dont have parents? who puts bread in the fridge? why is the fridge so empty? Why does it matter that the milk is PASTeRized? Why are the parents coming to the door for breakfast when thry can make it themselves THeN cone get me?