Which amonst the following will give a pleasant smell of ester when heated with ethanol and a small quantity of sulphuric acid?

The correct option is A ${\text{CH}}_3\text{COOH}$
Any carboxylic acid on reaction with an alcohol in presence of concentrated sulphuric acid gives an ester.
In the given options, only ${\text{CH}}_3\text{COOH}$, i.e., ethanoic acid on reaction with ethanol in presence of concentrated sulphuric acid will give an ester (ethyl ethanoate).
This reaction is called esterification reaction.
${\mathrm{CH}}_3\mathrm{COOH}\left(\mathrm{aq}\right)+{\mathrm{CH}}_3{\mathrm{CH}}_2\mathrm{OH}\left(\mathrm{aq}\right)\stackrel{\mathrm{conc}.H_2{\mathrm{SO}}_4}{\to }{\mathrm{CH}}_3{\mathrm{CH}}_2{\mathrm{COOCH}}_3\left(\mathrm{aq}\right)+H_{2}O\left(\mathrm{aq}\right)$