Roll-out switch monitors flame - when a ______ or _______ is misaligned and causes a flame roll-out. It may be caused by a cracked ______ _________, rusty ________s, or a poor _______.
a) Formation; burner; pilot; exchanger; vent; ignition
b) Ignition; burner; pilot; exchanger; switch; valve
c) Pattern; ignition; sensor; exchanger; duct; valve
d) Stability; sensor; switch; exchanger; duct; induction