Reduction of alkyl nitrites yields

Which of the following possess powerful mustard smell (and are called mustard oils)?

$A$ compound $X$ with formula $C_4H_{11}N$ reacts with $HNO_2$ to liberate nitrogen and produce compound $Y$. The compound $Y$ on treatment with $I_2 / NaOH$ produces a sodium salt of a carboxylic acid. The compound $X$ is

The relative basic strength of the compounds is correctly shown in the option.

Which of the following reacts with $CHCl_3$ and $KOH$ to produce $RNC$?

In the above chemical reaction,intermediate $X$ and reagent/condition $A$ are: