The number of isomeric amines possible for the formula ${\mathrm{C}}_3{\mathrm{H}}_9 \mathrm{N}$

Given, Isomeric amine
The number of potential isomeric amines in the formula

Isomers are all those substances that have the same molecular formula but have different chemical characteristics. Amines are ammonia derivatives that have a nitrogen atom that is basic and has a single pair of electrons.

The molecular formula for the four amine isomers is  ${\mathrm{C}}_3{\mathrm{H}}_9 \mathrm{N}$.

The right response, then, is A. 4.