A flame scanner
(1) requires a photoelectric cell(2) responds to temperature changes
(3) requires a clear line of sight to the flame
(4) produces a steady voltage signal
a) all of the above are correct
b) 1 & 2 are correct
c) 1, 2, & 4 are correct
d) 1 & 3 are correct
e) none of the above
Answer: D