d. How do you know [it is/they are] working?
1 [] Tested it/them
1 [] It/they went off because of smoke
1 [] It/they went off while cooking
1 [] Changed the batteries
1 [] The light is on
1 [] Beeps when battery is low
1 [] Other (Specify) ____
e. Any other way?
[] Yes (reask 11d and e)
[] No