I understand that once a player is put on the 40 man roster, they have three option years.   And I understand that once a player is out of options, you can send a player to the minors for a fourth year (after addition to the 40 man roster) even if he is in the ML roster if you designate him for assigment and he clears waivers.  My question is:  Let's say a player is in the minors when he burns his last option year.   Can you simply leave that player in in the minors after this last option year to use the fourth year in the minors (after being put on the 40 man roster) that way?    

As long as he's on the 40, you can keep him in AAA forever.

Thanks