An organic compound A upon reacting with NH_3 gives B. On heating, B gives C. C in presence of KOH reacts with Br_2 to give CH_3 CH_2 NH_2. A is:

An organic compound A upon reacting with $\displaystyle \mathrm{NH}_3$ gives B. On heating, B gives C. C in presence of KOH reacts with $\displaystyle \mathrm{Br}_2$ to give $\displaystyle \mathrm{CH}_3 \mathrm{CH}_2 \mathrm{NH}_2$. A is :