Answer & Explanation
A) cinema projectors
The carbon arc lamp was the first widely-used type of electric light and the first commercially successful form of electric lamp.
Here are the Carbon Arc Lamp Uses :
-Super bright light, capable of lighting a large length of street or a large factory interior.
-Was the ONLY electric light available to light large areas from 1800 - 1901.
-Was cheaper to light streets with the arc lamp than gas or oil lamps.