Which substance when boiled with $\mathrm{NaOH}$ will evolve ${\mathrm{NH}}_3$ ? 

• In general, when an amide is boiled with sodium hydroxide solution it forms $\mathrm{RCOONa}$ along with the evolution of an ammonia gas.

${\mathrm{RCONH}}_2+\mathrm{NaOH}+\mathrm{Boil}\to \mathrm{RCOONa}+{\mathrm{NH}}_3$

• Acetamide is an organic compound and the simplest amide that is derived from acetic acid. Its chemical formula is ${\mathrm{CH}}_3{\mathrm{CONH}}_2$.

So, when acetamide is boiled in a caustic soda solution which is also called sodium hydroxide, ammonia is evolved.${\mathrm{CH}}_3{\mathrm{CONH}}_2+\mathrm{NaOH}+\mathrm{Boil}\to {\mathrm{CH}}_3\mathrm{COONa}+{\mathrm{NH}}_3$

Therefore, option (C) is correct.