909. Which of the following labeled items of the illustrated air register and burner assembly represents the poke hole cover and would be temporarily removed to poke through a clinker

Item 13 is the poke hole cover, a hinged access point on the burner front used to break up clinkers with a poke rod. This cover's size and position align with the area where clinkers form, unlike the other labeled components which are levers or small, fixed fittings.