The correct option is(C): methenamine.
Amides react with bromine and caustic soda to give their corresponding primary amines. Thus, acetamide gives methanamine. This reaction is known as Hofmann's bromamide degradation reaction.
\(\underset{\text{acetamide}}{H_3C-\overset{\underset{||}{O}}{C} - NH_2} + Br_2 + 4KOH \ce{->[343K]}\)
\(2 KBr + K _{2} CO _{3}+ \underset{\text{methanamine}}{H _{3} C - NH _{2}}+2 H _{2} O\)