In the given figure of a rotary melting furnace, what does the question mark depict?
(a) Steel shell
(b) Exhaust box
(c) Refractory lining
(d) Molten metal
The question was asked in an online interview.
This intriguing question originated from Rotory Melting Furnace in chapter Metal Furnace and Practice of Casting-Forming-Welding II