Fuming sulphuric acid is a highly corrosive acid.
Therefore, the material of construction used with it must have good corrosion resistance.
Monel is a nickel-copper alloy.
It has very good resistance to many corrosive environments.
Because of its nickel and copper content, Monel is widely used where ordinary steels may corrode rapidly.
Nickel has good corrosion resistance, but Monel is more suitable in the given options.
Carbon steel is generally not suitable for highly corrosive acid conditions.
Stainless steel type 304 may also suffer corrosion in strong acid environments.
Therefore, a suitable material of construction to use with fuming sulphuric acid is:
\[
\text{Monel}.
\]