单项选择题

When does auxiliary burner of rotary nozzle incinerator begin to work? ()
Ⅰ.hen igniting
Ⅱ.he sludge for dealing with is too much
Ⅲ.efore stopping incinerator

A.Ⅰ+Ⅱ
B.Ⅰ+Ⅲ
C.Ⅱ+Ⅲ
D.Ⅰ+Ⅱ+Ⅲ