In the reaction sequence $2CH_3CHO$ $\xrightarrow{OH^{-}} A$ $\xrightarrow{\Delta} B$; the product $B$ is

Given below are two statements:
Statement $I$: $H_2N-CO-CH_2-CH_2-CO-CH_3$ under Clemmensen reduction conditions will give $HOOC-(CH_2)_3-CH_3$.
Statement $II$: $CH_3-CH(CH_3)-CH_2-CH(Cl)-CO-CH_3$ under Wolff-Kishner reduction conditions will give $CH_3-CH(CH_3)-CH_2-CH(Cl)-CH_2-CH_3$.
In the light of the above statements,choose the correct answer from the options given below:

The addition of $HCN$ to carbonyl compounds is an example of

Which among the following has the lowest boiling point?

The major product of the following reaction is:

Which of the following reactions gives a product with a $C=N-N$ linkage and a yellow precipitate?