A produces brisk effervescence when sodium bicarbonate is added to it. Therefore carbon dioxide is evolved. Hence it's an organic acid with two carbons, ethanoic acid- CH3COOH.
CH3COOH+NaHCO3→CH3COONa+CO2+H2O
We know that esters are sweet smelling substances that are used in perfumes. These are formed
when a carboxylic acid reacts with an alcohol in presence of conc. H2SO4.
Since, new compound A (i.e., ethanoic
acid) reacts with ethanol (an alcohol) in presence of conc. H2SO4 to form a sweet smelling substance which is used
in perfumes, therefore C must be an ester, i.e., ethyl ethanoate.
CH3COOH+C2H5OHConc.H2SO4−−−−−−−−→CH3COOCH2CH3+H2O
Option A is correct.