Which TVL is the concentration at which no exposure of any duration should be permitted?

In tactical fire fighting, the term "exposure" refers to a:

A) line where structures or human development meets or intermingles with vegetative fuels. B) large, uncontrollable fire that crosses natural fire barriers. C) structure with no limits on the area of combustible construction. D) structure or separate part of the fireground to which the fire could spreaD)

Many dental practices require a(n) ____________________ on invoices before payment can be made

Fill in the blank(s) with correct word