The compound responsible for the pleasant scent of fruits and perfumes belongs to the class of

Esters (alkanoates) are the class of organic compounds responsible for the pleasant, fruity scents found in many fruits and perfumes. Esters are formed by the condensation reaction between an alkanol (alcohol) and an alkanoic acid (carboxylic acid) in the presence of a concentrated acid catalyst:

\[\text{Alkanoic acid} + \text{Alkanol} \xrightarrow{\text{H}^+} \text{Alkanoate (ester)} + \text{H}_2\text{O}\]

For example, ethyl ethanoate (CH\(_3\)COOC\(_2\)H\(_5\)) has a fruity smell resembling nail polish or pear drops. Different combinations of acids and alcohols produce esters with distinct aromas - banana, pineapple, apple, and many others.

The other options are different functional group classes with different characteristic properties:

• Alkanamides (amides, R-CO-NH\(_2\)) are generally odourless solids.
• Alkanones (ketones, R-CO-R') have sharp, often solvent-like odours - not fruity.
• Alkanals (aldehydes, R-CHO) tend to have pungent, irritating smells at low molecular weight.