Which of the following has the most acidic proton?

Identify $X$ and $Y$ in the following reaction scheme:

Assertion : $\beta$-Keto carboxylic acids lose $CO_2$ when heated at about $370 \ K$.
Reason : An enol is first formed by loss of $CO_2$,but it readily tautomerises to the more stable ketone.

Which of the following statements is true regarding $HCOOH$ (formic acid)?

$CH_3CH(I)_2$ $\xrightarrow{KCN}$ $\xrightarrow[\Delta]{H_3O^{+}} ?$ Here the end product would be

$CH_2=CH-CO-OCH_3$ (methyl acrylate,bp $81^\circ C$) + $CH_3-CH_2-CH_2-CH_2-OH$ (n-butyl alcohol,bp $117^\circ C$) $\xrightarrow{TsOH, \Delta} (A)$ (bp $145^\circ C$) + $CH_3OH$ (bp $65^\circ C$). Product $(A)$ of the above reaction is: