Which compound gives acetaldehyde upon reaction with aqueous $KOH$?

Which of the following is an example of $S_N2$ reaction?

The ${S_{N}2}$ reaction of an asymmetric carbon compound always gives:

When chloroform is treated with conc. $HNO_3$,it gives:

Given below are two statements:
Statement $I$: The conversion $CH_3-CH_2-CH_2-CH_2-Cl \xrightarrow{OH^{-}} CH_3-CH_2-CH_2-CH_2-OH + Cl^{-}$ proceeds well in a less polar medium.
Statement $II$: The conversion $(CH_3)_3C-Cl \xrightarrow{OH^{-}} (CH_3)_3C-OH + Cl^{-}$ proceeds well in a more polar medium.
In the light of the above statements,choose the correct answer from the options given below.

Which of the following will give acetaldehyde upon reaction with aqueous $KOH$?