Or Airway. according to my kids. Even though B is not there now he taught Princess the beginning of the ABC's using a mnemonic from school. "A is for Airway, B is for Breathing, C is for circulation, D is for disability...." so she has taught Stinky the beginning of the alphabet using the same device. Princess got some interesting looks when she was in preschool and would come up with 'Airway' for the classic what does "a" stand for and draw a picture. How do you draw a picture of an airway that is appropriate for preschool??
Thankfully she does not know the 'OPQRST" mnemonic for pain that would be interesting to explain.